Corporate debt is high because DEBT IS STILL CHEAP (fed is changing that). Of course they're going to borrow fuckloads of money, it's practically free by some measures!
The indexing "bubble" is actually a correction for a lack of value from active funds. I don't expect the correction to be corrected.
The cryptocurrency bubble is tiny. 65 billion? That's a rounding error.
5 Stocks accounting for most of growth is troublesome when corrected, but still not catastrophic. If we lose ALL of that growth then we go back to 2016 levels? Ok.