To confirm, what makes Coinbase different is that it's not a lender?

It's kind of absurd the level of failure in crypto lending. Putting aside anyone with criticisms of all things crypto these should all be based on the very basic and long established business model of taking deposits, making loans, and paying interest. There shouldn't be anything inherently difficult or "scammy" in that and it should be a successful business pillar in the crypto space. Besides the basic business your two other main priorities should be risk mitigation and dealing with liquidity issues. Surely long term some well run company ought to be able to sort this out.

I haven’t ever seen a crypto lender stay solvent.

Unless:

A) The money never leaves the platform such as with collateralized margin lending for shorting / leveraging.

B) The money is collateralized such as on DeFi with AAVE.

BTCJam gave small, well-diversified loans based on credit scores, reputations, business ideas, and identity verifications. They iterated and tried almost everything but they couldn’t get enough money that left the platform to ever return to the platform.

Scamming the banks seemed to be way more profitable and lucrative than using borrowed money for economic activities more productive than the borrowed interest costs.

Huh? It looks like it was saying the three are Celsius, Voyager, and BlockFi, but it’s missing a much larger one, Genesis. Although that maybe be going bankrupt to if it can’t get support from its parent company DCG.