These days I see new L1/L2 incentives to boost TVL again, and old users are complaining "mining and selling," which makes me think of options: who is actually eating the time value?

The buyer is actually buying "possibility," and every day when they open their eyes, they are slowly losing money over time. Even if the market doesn't move, they can still lose, which is quite like you constantly refreshing/retrying on-chain data, waiting forever and still being stuck in line.
As for the seller, to put it simply, they are collecting rent on time. It looks very comfortable most of the time, but when a big wave comes, they have to endure it, and the psychological pressure is much greater than you might imagine.
Anyway, I care more about whether I can hold on and sleep well. It’s okay to be slow; don’t sell yourself as an insurance company just for that small premium.