Well, there are several things going on here.
-- "Hesitate with investing" isn't idiomatic. "Hesitate to invest" would be better.
-- But: "hesitate to invest" isn't a very good translation of "sparen."
-- "Will be the reward" isn't a great translation of "ernten."
-- "Unculture" isn't a very commonly heard English word.
-- Together with the above points, the parentheses, dash, caps, and "aka" all contribute to making the suggestion in #1 read very awkwardly.
-- I searched the German phrase and didn't find anything, so I'll assume it's your invention, not a familiar phrase or saying in German.
It seems to me to be mixing metaphors in an awkward way: the first part has to do with spending/saving money (maybe that's not even really a metaphor here), but the second uses the metaphor of reaping or harvesting.
There are familiar English expressions having to do with reaping what you have sown, i.e. harvesting what you planted. So maybe the idea could better be put in a way similar to that, in English and maybe in German as well.
Relatedly, is Unkultur supposed to suggest Unkraut?
So, taking all that together, here's one shot at it:
"If we don't plant the seeds of culture, we will reap the weeds of barbarism."
I'm sure that can be improved on, though.