yes there is only 21m btc but iI think that it is not enough
How about 21m x 100m, isn't that still not enough?
it make anyone reach just by bying and hodling it
This one is a misconception about Bitcoin, one cannot realize a profit if they don't sell, simply buying and holding will never give an investor a profit unless he sells.
we normally get rich by working, studying or something else but not hodling
No one got rich from studying, a person need to apply what he have learned in order to take profit from it, same goes to holding, one can't become rich with just holding alone.
there is that guy who keep all his time studying and working and get paid just to pay rent, food and his family (life should be like that)
there is that guy who never studied or work just get some btc and hodl it

This simply shows that people who can take advantage of the opportunities lurking around them will surely get rich. Btw, as I stated, holding will never make anyone take a profit, selling is.