I'm also far from an economist, my best credential on the subject matter being that I get some shares as part of my compensation package. But here's an interesting point out of a discussion with a colleague who does, in fact, work in the financial services industry:
His take is basically that, in financial services in particular, there's somewhat of a Trump-bubble going on in that the industry is expecting and hence betting on at least a partial but (from their POV ideally full) roll-back of post 08 checks and regulation. Perhaps even a move towards further de-regulation. The expectation of future profits to be gained out of this is leading to soaring share prices.
There are, of course, at least two major risks involved here: First of all, the expected developments might just not materialise. This would obviously leave the industry overvalued with all the implications of that. Risk #2 is way scarier, though: de-regulation DOES happen and an already over-confident industry goes to town exposing the global economy to basically pre-08 conditions, including - crucially - the potential for a possibly even bigger 08-style crisis.
Or at least that's basically what my understanding was out of the conversation. It's quite scary, actually. I do not recommend speaking to financial services experts if optimism is your thing.