the number1 activity for any aisofter is to spend money.
And as soon as your kit is ready with everything functionnal and you have nothing more to buy (after 5 or 6 years into it ), internals start breaking and the spending can go on.
wanna get out of airsoft? you need to spend more to make your aegs sell-able so that they appeal to clients.
out of airsoft? just wait a few years till you catch the bug again.
there is no end.