Providing a framework and goal for ex-Soviet colonies to modernise and democratise is the EU's best achievement.
You're right about European enterprise. The US has the richest and most influential tech companies in the world - Amazon, Facebook, Google, Apple etc. The EU, with its much larger population, a larger internal market and equivalent educational resources doesn't have anything at all to rival any of them. The single market is more concerned with selling Audi's and BMW's, so the digital single market in services doesn't exist. EU regulators focus too much on breaking up dominance rather than nurturing the creativity that allows companies such as Amazon to achieve dominance, thrive and provide wealth and influence.
I've wanted out of the EU for well over a decade because it is clear how uncompetitive and archaic it is, a huge, unnecessary political project that is continually beset with crisis, gridlock and disparate conflicting interests. If I thought the project was worth pursuing, I would be the first to advocate Britain being right in there, taking the lead and contributing as much as anyone, but it is clearly an outdated model, a 1950's solution to a 1930's problem, completely unfit for the modern world.
How has the EU harmed the chances of startups in Europe, and do you have concrete examples of both the startups in question and how their prospects have been harmed?