It depends on how much expensive merchandise you own. People forget just how quickly things add up. As a single example (out of hundreds in an average home), most people won't even remember to add their toaster to the insurance claim. And even if you remember to claim "a toaster", insurance will pay you $20 for the most basic toaster possible - rather than the $120 you spent on an 8-slot, temperature-aware model.

If you're claiming < $10k and you can live with receiving less back, you may be better off doing it on your own. If you're claiming much more, a (proper, non-scammy) insurance agent is going to multiply your return by an unimaginable amount. The majority of people are getting back less than 50% of their potential insurance payout. It can be worth paying an insurance agent $2000 to get back $30k instead of $10k.

Source: not an insurance agent or anything related; just remembering a Reddit thread where multiple people shared the gap between what they assumed they were eligible for, vs. what an agent squeezed out for them. Normal people don't know how to describe their possessions in proper detail. A decent insurance agent will ensure that what is being replaced is of equivalent value, rather than a bunch of the cheapest generic products.