It's true, bitcoin itself is investment but to make profit, you'll have to wait for long period for the price to go up.
Waiting is part of investing as well, either you just sit and wait till the price goes up or you can just go and invest your bitcoin in some trusted site however the same as waiting for the price to go up there is actually some risk involved , well anyway everything has some risk involved and there is no such thing as risk free
Yeah, some people can consider investments as gambling. In their point of view, investment is like gambling because investors are trying to earn money (like gamblers), but in investing they are waiting for their assets to raise and if does or does not that is where the gambling is. Also, if it is indeed rising then the gambling there is when to push the withdraw button. So basically, some think that investing is indeed gambling because it is also not risk free.