> Round trip efficiency of hydrogen is at best 50%

In fact, even this level of efficiency may be sufficient. Solar panels are so cheap that if we had affordable, long-term energy storage options, even with such efficiency, we would have completely abandoned fossil fuels. But, unfortunately, storing hydrogen is difficult and dangerous. It is not like natural gas.

> It's not nearly as stupid as making ethanol from corn (which is an energy-negative process) but it's close.

Ethanol is produced from corn not for energy purposes, but for food security. It's like a placeholder for real corn so that if there's a crop failure for a couple of years, the low-iq idiots who think it's stupid to make ethanol from corn don't starve to death.