Insurance is an industry built on denying claims - legitimate or otherwise.
Attributing your experience to the entire industry is not right. Indeed, some keep their premiums lower, by aggressively managing payouts. There are others, who are much better, but you pay more. Unfortunately, most seem to shop price and get what they pay for.
I bet most have had frustrating experiences, in no small part because a claim is made under stressful circumstances. A loss. Nevertheless, there is a contract between the boat owner and the insurance company. It’s a bet, no different than a roulette table. The boat owner is betting they will have a loss, the insurance company is betting they won’t. The terms of that bet are very specific. What, how, value, required actions, exclusions, etc, etc. When buddies have had trouble, it’s usually because the event simply wasn’t covered. They hadn’t placed that bet, any more than asking to be paid out for a roulette number they didn’t bet on. I’ve had two marine claims in my lifetime. One was storm related, the other was from a collision, while I was tied up to a mooring (and asleep btw). Both paid fully and promptly.
Finally, for every legit story of an insurance company trying to withhold a claim, I can tell two of people trying to get free money from an insurance company, by inventing a claim. A very common one this time of year is hurricane haul coverage. Our marina’s winter storage contract is paid by the square foot of ground covered and is fully inclusive of hauling, bottom washing, blocking and launching. Every time there is a late season named storm, someone will ask the marina to haul them permanently for the winter, but split the bill for the hauling and launching so they can make a claim. The owner has suffered zero loss, they simply incurred their anticipated winter charges. The marina refuses to do it and be involved in the fraud. When Sandy hit many years back, I was already fully decommissioned and waiting to be hauled. It’s was something like Oct 30? Therefore, I made no claim. Others tried, some who had hauled weeks earlier.