Earlier quoted context omitted.
It's called malinvestment, and it's tied to monetary policy. When the central bank churns out money, the lower interest rates discourage banks from lending, making it harder for small businesses to collect capital that way. The lower interest rates simultaneously drive investment from bonds into the stock market and real estate. Look up Business Cycle Theory
This does not explain why VCs are willing to invest in business models tha light cash on fire for growth in the hope of reaching a dominant market share and establishing a moat around the business. VCs believe in network effects, VCs believe monopolies are worth burning cash to achieve, VCs believe operating businesses can achieve what software businesses like google and Facebook achieved. Question their belief but d…
VCs aren't some unique species that have cracked investing. Human nature is the same as always: people will do stupid stuff. If someone turns up with a check for $100m, you don't check to see whether you can invest it safely. You become a true believer, you gather assets, and if you weren't a true believer at the start you will be after you make enough...it always ends badly but this is why cycles happen.
In fact, the last cycle has been particularly unusual because we have actually see the bad firms driving out the good ones (I don't know about VC but it is happening everywhere else). And this is definitely due to monetary policy.
You are right. At the level of the investment, people aren't saying we should seed this company because of monetary policy...but no-one says this in any bubble. Rather what happens is that the demand for securities goes up and finance finds ways to fill this demand. Human nature being what it is, this always ends badly.
To say this another way: people will find endless ways to rationalise a bad decision. And if someone is paying you to make bad decisions sound good...well then, what do you think will happen?
Btw, just generally, I think VCs are less sophisticated than the average investor. The current environment has just been very forgiving. I don't think we will see anything like this again (if central bankers lose control which seems inevitable), literally firms with billions in cumulative losses trading for $10bn+. These IPOed firms will probably destroy hundreds of billions in capital alone.