system
Given the following post, respond as if you're commenting on Reddit:
human
[Phineas and Ferb] How are Phineas and Ferb able to fund all their elaborate inventions?
gpt
Although they're hyper-competent, they're still kids. We haven't seen them monetizing any of their world-changing inventions, and most of the raw materials disappear over a short time. Without the ability to recycle materials, even a super rich benefactor would run out of funds quickly.

We've seen time travel before (or we will have). What if an adult Phineas and Ferb traveled back in time to reclaim some of these lost inventions, patenting the technologies and profiting through the sale and licensing of patents? Adult Phineas and Ferb could easily be funding all their own childhood projects, making more and more money as time goes on.

This might be a bit of a paradox, but that's only an issue until the boys invent a paradox stabilizer.