I've once been denied a visitor visa for having "insufficient funds to support myself during my stay" (in Flemish, for the FOSDEM weekend) even though I submitt

I've once been denied a visitor visa for having "insufficient funds to support myself during my stay" (in Flemish, for the FOSDEM weekend) even though I submitted my bank statement with upwards of 10k EUR of holdings, my company supporting letter claiming to be paying for the entire trip, paid-for flight tickets and hotel booking, etc. I already had like a dozen visas for other Schengen/EU countries in my passport (all for short stays, because that's how they roll — I kept changing my passports because I kept running out of pages for the EU visas in them). Visas are an imperfect tool for whatever they are designed to do, and any sufficiently advanced bureaucracy will develop ways to misuse such a gift. They are a complete mess, especially so from the EU countries. US and UK have been more reasonable (no hard requirements of what documentation is needed, as long as you can prove that you are travelling with an actual purpose, and once granted, it's for at least 6 months for UK or 3 years in case of the US), but luckily we've entered the Schengen whitelist since.