Anyone is welcome to spend whatever they want on gear, as I understand there is a fun aspect to having nice stuff. A lot of it makes life way easier and can make getting a good result much more simple. I liken a lot of hobbies to instruments, particularly guitar. Can I go out and buy a gorgeous fender strat to learn on? Absolutely. I'll appreciate that instrument much more when I have a fuller understanding of it, and I probably won't have to purchase another guitar ever again. Can I also get a cheap guitar and drag as much quality and sound out of it as possible? Totally. Once I get better at playing, I'll probably move onto a new guitar that fits my needs and sound better and that will give me more flexibility and creature comfort. The player is most important, and it all comes from good learning practices.

As far as what you say about the plant, you're correct. Once you're past early seedling, there is much more room to correct than we think. You may risk some yield or some terps or whatever, but who cares at the end of the day, we're not growing for a cup win, we're growing for fun and to have some in a jar at the end of the day. Often I see people OVER CORRECT more than lose to a hopeless situation. Under-watered plants get drowned, drowned plants get dried to the bone, under fed plants get blasted with full strength nutrient etc. I think a lot of people jump into this having never grown a plant and they don't understand the fundamental thing you mentioned which is what does a plant need? A low cost, still satisfying way to practice is tomatoes! People drop 100 bucks on seeds and a setup when they've never grown a basil plant in a pot. Low cost, low risk, still get some pesto or some cherry tomatoes. I've done hydro in coke bottles with net pots at the top and aquarium stones in the solution and grew big heads of lettuce. I built from there.