The nice thing about investing in the markets is that eventually, you can also get out much more than what you put in. The magic of compounding. You also don't screw the younger generation while you're getting paid.
"Magic" of compunding cannot exceed the real growth of actual economy in the long run. Sooner or later something "unexpected" happens - a crash, collapse, a leftist redistribution scheme, a civil war, confiscation or else.
Usury can work only for the few in limited scope. You cannot base the whole society on usury. And money is only a very useful artificial convention which breaks down if treated as actual reality.