the idea that new comics are printed in too great of number to ever be worth anything is exactly what has made comic books of the past valuable. eventually, they get beat up, eaten by little brother, or just thrown away with other childhood toys (also of some value).
Is it a risky investment? less than playing the market, because it is a known factor that there will be less, of good quality, over time.
Is it a stupid investment? not if you enjoy the collecting and maybe reading, and it's a much cheaper speculation than trying to play the stock market.
So, what should you buy? buy what you like, and enjoy them, but take care of them too. many years down the road you may have one of the few surviving issues of the next big score.
but if your buying things that already have a high value, beware and know what your buying, there are a lot of hustlers out there trying to pass of reprints as original copies.