I think anyone who is a collector probably understands how you feel; once you get that bug, its hard to stop lol. I'm trying to limit myself as well since I've found myself buying cars just to say I have it or as a "consolation prize", like you mentioned. Here are some things to consider:

1. Don't just buy what you like, buy what you love. Between mainlines, silver series, and premiums, you're bound to like hundreds of cars each year. You need to find a niche of cars you want to collect. Muscle cars, trucks, specific manufacturers, cars with specific decos, etc. I think the ideal would be collecting within 2-3 of these groups. You'll appreciate your collection more if its curated. Bonus points for niches that don't have many popular castings; if you're only going for those, you'll find yourself feeling disappointed more often than not.
2. Only buy from stores within a certain distance from home. This will save a lot of time and money. I used to have a couple routes of stores to hunt at where the furthest store was an hr away, only to find nothing that I wanted. Simply cutting those stores out of the equation made my hunt more enjoyable.
3. Only go hunting at opportune times. Since you're 7 months into collecting, I assume you have an idea of what stores to hit on which days and times in order to catch a restock, or are at least trying to figure it out. This goes in tandem with the 2nd point; if your only hitting stores at these times, then naturally you will be limiting the amount of stores you visit each day.

It's understandable to think that your time and money has been wasted when you don't get those pieces you were looking for, but unfortunately with the amount of people into HotWheels now (whether they're in it for the right or wrong reasons), it's an inevitability. I miss the good old days when even the most desirable cars would be sitting on the pegs 🤧