The fewer investors will decrease the market price. The market price is influenced by the volume, therefore we must convince the public to believe that bitcoin is very influential for the future.
One thing is that a lot of people do not tend to correlate things in a way that is realistic and they just tend to see it the way they understand.
How will exchanges be increasing in number when they have no user at all on board or if the users are not increasing? i can remember the number of times the likes of Binance decided to close registration simply because they could not handle the number of users at that period of time and then had to upgrade before commencing new registrations, so for someone to say investors are not increasing, he might need to rethink that pretty well.