Solar City isn't a failure, it's part of Tesla now. Still selling panels, as far as I know.

Boring company is also not yet a failure, and has recently built several tunnels. Neuralink is an early stage research company and is still humming along. It may fail some day, but it certainly hasn't failed yet. As for Hyperloop, he specifically said he wasn't going to build it, and several companies are still working on it, including in China:

https://futurism.com/the-byte/china-maglev-vactrain-hyperloo...

None of these things are "failures". They may become failures one day. It'd be crazy if some of them didn't. But you can't count a research project as a failure just because it doesn't have a product yet.