It is annoying seeing lower levels in better cars, knowing they glitched the money to get them, but that's life. Nothing you can do about it, just try and enjoy the game.
I tend to try and go for unique rarer cars now, instead of the usual super cars everyone has, since it's seems more meaningful knowing I took the time to find one. Of course others are now duplicating these rare cars from others to quickly get them.
But at the end of the day, It's a game. So I've still enjoyed saving up for my first garage with two cars, then a 6 car garage and now recently moving up to a 10 car apartment with 8 unique cars so far.