I like how you compare it to gift cards:
blindmixer works similar to a gift card provider. Instead of gift cards, blindmixer provides you with coins, which you can trade for bitcoin. However, instead of taking a fee when conversing, as most gift card providers do, blindmixer will once in a while reclaim all the "dead" gift cards (coins) which have yet to be used. This allows us to run all of our services at cost, which provides clients with the lowest possible fees. This is done by rolling over the custodian every so often.
But that's also the problem I have with it: Bitcoin isn't a gift card, private keys are forever!
Alternatively say we would never exit-scam (obviously not our intention), would you rather pay a fixed fee of ~ 1% in return for a "promise" that we so long as bitcoin exists guarantee your funds?
That would also be misleading:
A. We cannot promise anything forever.
B. We cannot promise someone does not somehow exploit our software.
C. We cannot promise we do not get seized.
I appreciate being open about this, I just don't think people will exchange their Bitcoin for a gift card.
Maybe for small amounts if there's a useful application for it, just like I'm okay having small amounts of Lightning funds in a custodial wallet. But even though all the same limitations apply to for instance BlueWallet, they're not planning a regular "exit" by taking all user funds.