Something that may contribute is that life is fairly predictable in Europe, and by many accounts prosperous. This may sedate the entrepreneurial spirit.
Selling your labor to make a living is an entirely respectable choice. A comfortable life all the way to the end is more or less guaranteed. Labor protections are much more generous as well. In the US, starting a company is partly an attempt to escape wage slavery and toxic work environments. Somewhat exaggerated perhaps, but in the USA, the entrepreneur is celebrated while the salaried employee is pitied. (Unless when it's election season and all suitors crow about jerbs, jerbs, jerbs).
There is also an enormously amount of stored wealth in the existing infrastructure and built environment, much of it owned by families or collectively, and people enjoy continued long term robust family relations and social support structures nearby, cradle to grave. Generations of prosperity and fairly modest lifestyles see to that. This is lost to many Americans, when comparing snapshot measures like average yearly income or per capita GDP. But wealth - the measurable money kind and immeasurable chicken-soup-for-the-soul-kind is accumulated over time and regions like Flanders are positively rich with both. America - somewhat a cliche - MUST be sustained by growth, because the recurring costs of the necessities are so high. The built environment in America is basically a gigantic liability, only supported by a promise of future revenue. And the constant geographical movement of labor breaks apart families and existing support structures, constantly in need to be reconstructed. In this context, the promise of a fat payout after an IPO is a soothing balm.