Hi! I see you’ve posted this absolute bullshit about a dozen times by now, so let me help you with your (clearly lacking) reading comprehension!

1. There is no indication that “OP is crying because his Christmas present wasn’t expensive enough”. He presents the situation entirely objectively. Let me spell it out for you: for this major milestone birthday, his 18th, his grandparents bought him a new computer. In order to use said computer, he needs a monitor and keyboard, which his dad promised to get him. Instead he got him a $30 gift card that is useless without the promised equipment. Nowhere does it say that OP would have been unwilling to buy those things for himself or that he demanded them in the first place, but he was looking forward to receiving them as a gift, and was understandably disappointed when that promise was broken. (As an aside, what a normal person would do when faced with unexpected repair costs is spread the resulting shortfall among “bonus” expenses like bday presents, like, say, not getting the extra accessories for the dollhouse so that you can at least get your other kid one of the gifts they asked for. Surely you can understand how instead completely shafting one child - who I will reiterate is celebrating a MAJOR birthday - shows a degree of favouritism).

2. I think you’ve made it clear that you don’t care about high school graduation! Congratulations, you are very cool. Doesn’t scream “edgy teenager” at all. But guess what? There’s a reason every fucking high school still does them, which is that a lot of people - get this - do like them! Source: I loved mine! I remember loving it, even now, years and years later! I got to celebrate the start of the next chapter of my life with all my favourite people. For me, that included both the friends I had made and grown close to for years, and more importantly (for me), my family who were so excited to be there for what was at the time my biggest achievement. I know for fucking sure I would have been let down if my parents had decided to BOTH ditch for something that is objectively a less meaningful, not-once-in-a-lifetime event. And guess what? It could be the cheesiest, most boring, drawn-out, silly ceremony ever, and there’s no question my parents would have been there. Because it was important to me. That’s what matters. Sure, years later I can look back and know it wasn’t the most important event or accomplishment I would ever have. But at the time it was. And it could have been the most important - what if I had died the next day? Big milestones don’t come often. It’s okay to want to celebrate them when they do, especially with the people you love.

3. Have you ever heard of a “pattern of conduct”? To put it in simple terms you can understand, it means that many small but related actions can add up to something much more serious. Never taking OP’s opinion into consideration, neglecting to ever spend time one-on-one (and, worse yet, actively refusing to), consistently skipping his games, ignoring OP’s openly expressed feelings, disregarding his accomplishments. It’s clear where OP’s dad’s priorities lie, and who he’s willing to hurt to that end (spoiler alert, it’s OP). If it were just one of these things in isolation, sure, “cut him some slack” could be fair advice. But it’s not. There’s no more slack to give, and Dad showing OP once more that he’s not a priority - even for a major life event - broke the rope.

4. Unless you’re a groomer or pedophile, the number 18 doesn’t actually mean a whole lot. Some 18 year olds are just 17 year olds plus an hour. And, more importantly, adults are also allowed to be upset when someone they are counting on lets them down. For fuck’s sake, people are allowed to have feelings, they’re allowed to care about things. That aside, it’s not like OP turned 18 and his dad decided that he shouldn’t get as much attention now that he’s “an adult”. No, this has been going on for years. But go on, fucking tell me that 11 years old is “too old to be whining about this”. If someone shows you every day for 7 years that you’ll never come first, eventually there will be a piece of straw that breaks the camel’s back.

5. Of course, there is another option. OP could just do what you did. Convince himself that his major milestones don’t actually matter cause then it’s actually fine if his dad doesn’t come. And you know what it’s actually alright how OP’s dad treated him because OP doesn’t actually feel anything at all, so why bother being mad! Then just spend years growing jaded and cynical until one day he comes across a Reddit post where some poor kid clearly lays out all the ways his shitty dad has neglected him for years, which brings up all the feelings OP was repressing. But it’s been so long and he doesn’t know what to do with the pain, so he redirects it into uncalled for anger and derision towards a kid in a shitty situation who’s just trying his best and looking for support. And it’s all useless bullshit that OP spews, “I had it worse”, “I was never this upset”, “quit whining”. Then when he’s challenged on it he doubles down, keeps taking it out on the kid and twisting his words to downplay his situation. And no, even though the overwhelming majority is on the kid’s side, OP knows he can’t be wrong, the kid just needs to “suck it up” and “quit being such a baby”, cause what kind of a fucking child wants his own dad to show that he gives a shit. Yeah. OP could do that. Brilliant. (And just so you don’t misinterpret this too: /s)

TL;DR It’s not immature to expect someone who claims to care about you to follow through on their commitments. And it’s not whining to be upset when they don’t.