Maybe what you mean is that  as the price increases in the future, the exponential growth will slow down, which is true. However, what makes the argument is that bitcoin is going to be scarce as well, that's why it is the most sought asset in crypto because of this one. Yes, the growth might stall, but with more people looking to buy at whatever price it is, I doubt that there are less buyers that are going to enter, on the contrary it might balloon as everyone is looking to make bigger profits in the future.