I hear ya. I am getting more comfortable with this read on things: the market has just grinded higher for quite a while over the last 10 years until the pandemic. A mindset evolved that sure the markets are great, but they had climbed too high to buy in at that point.
Then came the pandemic.
Immediate response was panic in that it was generally felt the market was a bit over-valued and anyone even a little nervous was now paniced, and for good reason.
But three things set the stage: everyone knew markets are good but a good entry point is key (and they had been non-existent for years), the Fed gave more than a few signals that they would be there to take the bite out of the softness in the market if not the economy, and lastly, as Racket said, there was nowhere else to park one's money with any solid chance for appreciation.
What you got was a very fast, aggressive, rebound, and one with staying power.
The reason i feel comfortable in this belief is that clearly investors over the last two months aren't stupid, but understand that they simply cannot afford to miss out on the once per generation opportunity to enter the next bull market with - and this is the important part - the confidence that the economy will improve within 18 months to 2 years, and anyone who waits that long will be damned to the all too familiar realities of a sideways market or at best, a slowly appreciating one.
Again, the markets aren't stupid. This surge only makes sense when considering what came before, Fed willingness to have our backs, nowhere else with such good returns, and the belief that at worst, things are expected to be better within a couple of years and that is a reasonable time horizon for current investors.