The crazy thing is, /r/wallstreetbets is fully cognizant of this fact. They just do it anyway for the lulz. They egg each other into increasingly degenerate highly risky options trading, and huge losses are lionized just as much as huge gains.
Don't let nit-picky facts like that institutional investors control substantially more capital than retail investors get in the way of a good narrative.
No, there is no good reason for Tesla to be valued the way it is - but there is no shortage of people willing to buy it without putting too much thought into the price, either.