The US investors just have so much more disposable cash they can risk. EU investors are looking for safety because losing 100M EUR means they lost literally everything. Their "risky volatile investments" part of the portfolio is 1-5M EUR in total, usually even less - and split that between at least 3-10 startups. And there's much less people with money overall, so you can't raise large enough VC funds.
The usual EU investor is simply going to buy some real estate instead of participating in VC funds - still great returns, very low risk. The more progressive ones will maybe try some real estate development projects. No need to think about this software thing. The angel investors I met with that had portfolios of 5-20M EUR wanted to invest 20-50K EUR into our startup, definitely not more.
It might not be that they are "uniquely ambitious and generous" but rather that the US has a much greater wealth disparity on average, so the rich are much richer and presumably have a lot more to invest.
They have lots more money. Which probably originates to climatic and geographic reasons, but more recently due to the _massive_ destruction of wealth in the world wars. It's very hard to build up a wealthy middle class when every few decades millions die on the battlefield.
Pension funds. European pensions are run as insurances and/or financed via taxes. Thus, there is no investment capital from pensions. The U.S. is quite the opposite, and that fact alone probably explains > 60% of the gap in VC financing.
some people just use the governmental pensions (like in Germany) which aren't necessarily from a fund so they aren't funds at the beginning.
I heard France just aloud pensions funds to use for VC financing.
My opinion this is one of the big reasons for the lack of strong startup investments. The other one is the lacking financial union.
The usual EU investor is simply going to buy some real estate instead of participating in VC funds - still great returns, very low risk. The more progressive ones will maybe try some real estate development projects. No need to think about this software thing. The angel investors I met with that had portfolios of 5-20M EUR wanted to invest 20-50K EUR into our startup, definitely not more.