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Technically no. First, you have to know that Bitcoin can be broken down into smaller units of value called satoshi so the worry of people only having a max of 21mil investors shouldn't be a worry in the first place. From that you can pretty much just assume that the value of Bitcoin would just increase in price the more people buy it since well, people start using sats exactly because more and more people are buying in the first place. As for miners they're still going to be relevant since transactions still run under them.
Yeah, there is a talk than one day (probably not in our lifetimes) the reward for mining will be halved so much as to pay the miners more in fees than from rewards, however, that's another story and question.
I do think everything is going to be great with BTC, for those who think of it as more of an investment - because they don't go into technicalities (which most of the times answer most questions related to BTC in different fields).