Don't just go with the total number of investors, but see the total number of users also. People being added daily to bitcoins is one of the biggest reasons why you should use bitcoins and invest in it. It takes years for bitcoins to grow with stability, and see the charts that show that Bitcoin has proved to be the best investment since its invention so far.
Bitcoin investors can be considered as bitcoin users. Hence, bitcoin investors and users are both same since as you use bitcoin for a purpose, you need to fund your wallet which can be considerd as investment since it is a part of the share of bitcoin.
For what reason people are touching bitcoin must be insignificant as only the userbase will matter for any achievment. We could not expect all the investors must use bitcoins similarly we cannot enforce all the users of bitcoin to hold it for long period. Still, they are part of bitcoin ecosystem and they are helping bitcoin to grow further with different levels of contributions.
When we are considering only about userbase of bitcoins, I believe it would be more than enough to get into it as an investor for a secured future. Yes, when bitcoin has more userbase, we can expect bitcoin will have huge values in near future itself.