Berkshire, Cash Piles, and Market Valuation

I've read a lot about e.g. Berkshire sitting on a huge cash pile because the market is overvalued. I tend to agree that the market *is* overvalued, but I'm wondering about the distorting effects of these huge cash piles.

Berkshire obviously stands out (they're sitting on $400bn), but overall I have to wonder if large cash pools aren't propping up the market. The fact that "someone" is there to buy up shares at a discount on that scale would seem to reduce the perceived risk of a major correction or crash. And ironically, I suspect the longer Berkshire et al pile up cash on the sidelines, the more this is likely to persist.

By analogy, this was the sort of thing that looked like it propped up the JPY for a long time – because of near-zero interest rates at home, e.g. insurance companies parked huge amounts of cash overseas…and the risk of them bringing the money home (and thus having to buy yen to do so) helped keep the value if the yen higher than it probably "should have been".

This is also a variant on musings I've had over the last decade about whether corporate cash piles could grow large enough to frustrate monetary policy – is there a point where an attempt to raise interest rates could confront massive enough pools of "cash" that the government finds that it can't really move economic behavior like it wants to? I feel like there was a brief episode of this in 2022 (interest rates rose and the market kept shooting higher for a while), but the prospect of (say) businesses deciding to act to avoid consumer defaults (and associated losses) by ignoring what they expect to be a shorter-term rate spike (especially if they're already well ahead of the rates they borrowed the money at) doesn't seem completely nuts, either.