These two facts are completely related. A wide array of competition is to be desired, not "biggest in the world."
Go two miles in any direction from our neighborhood, and you have multiple providers with gigabit or near gigabit speeds, including AT&T.
Regulatory capture indeed.
Additionally, Switzerland is all but drowning in money (in fact, they have to fight to keep the Swiss Franc affordable [2]) because everyone and their dog who can afford it parks their dark money there. That influx of wealth is reflected in the services and wages that the citizens get.
[1] https://www.avenir-suisse.ch/wie-dicht-ist-die-schweiz-besie...
[2] https://www.handelsblatt.com/finanzen/geldpolitik/schweizer-...
NYC sits at about 11k / km^2. Unless 10Gbps internet and up in Switzerland is only available in Geneva, there's clearly more than just population density at play.
1. As you may know half of Switzerland is filled with mountains, so building infrastructure there is actually not that trivial (no, the high speeds are not just in the big cities, they're everywhere).
2. Dark money in Switzerland hasn't been a thing for a while. The wealth comes from sensible policies like a sovereign currency, low taxes and reasonable levels of regulation and bureaucracy. All that money also makes everything expensive, so the extra money kind of cancels out when it comes to doing stuff inside Switzerland.