Here in my country, for a person to start investing in stocks, one must have a starting capital of roughly $100. The same goes for mutual funds. If we compare it to bitcoin where you can buy even the smallest fraction, the advantage can be seen clearly in favor of bitcoin. Also, you dont have to submit too much paper works during the application process. With bitcoin, everything can be done online, whenever wherever.
This is quite a very reasonable point looking at all the processes it takes to invest in stocks.
However, it may be simple for you now to invest in bitcoin but truth be told, not so many people are tech savvys and some people will rather you do it for them than understanding the processes of opening a wallet, buying of bitcoin either via P2P exchanges, debit/credit card etc. Considering all these, we may as well just say it is still going to be limited.