What are the major unsolved problems in defi?

needing the gas to swap one currency for another but not being able to swap anything into eth in order to get the gas to do the swap

vibe curator waterfall.market
/ 
master of ascii art
https://manifold.gallery/base:0xa7f27592542a13e10b69b55be528d6f48164ac8c

gas costs 10 cents, you have $1k in USDC, you need to swap into eth, but you have no eth in the first place so you can't swap any USDC into ETH.

gas should be able to be paid after the fact without needing someone else to front gas for you (think matcha, but the fronting is built into the transaction)