Wait what? (1+2+3+4+...

[BAndrew]

But why is it ok to put a limit on something that has no limit?

I don't believe that math is actually natural, I think it's a human invention to understand our surroundings, nothing more nothing less.

You don't "put on limit on something that doesn't have a limit". I think you don't understand what the limit really is. What I wrote (as I have said before) reads:
"the limit of 1/x as x approaches +infinity equals 0"

If math is not natural then are you suggesting that (for example) the pythagorean theorem wasn't true before we discovered it? If that is the case then why you can't create any theorem you want?