If you've bought enough exclusives when they first came out (before they go right up), especially BotCon ones that cant be sealed, I think it would offset anything you lose in the items you've opened up. And those out-of-packet general release items that are more than 15 years old would on average be equal or more than their retail prices at that time.
But yeah, a sealed collector of general release items has 2-3 times the value in their items bought in the last 10-15 years.

I've probably spent more than 100k over my 25 years of collecting... more if I count the cost of 12 BotCons as an expense to add several hundred toys to my collection.
The estimated (sellable) value of the collection is probably 150k though, while the replacement value would be at least 300k (most would need to be sourced in packaging to be complete and in good condition).
So I'd probably make a profit if I sold my collection right now, but since I have most out of packaging, if it was all suddenly lost, it would cost 2-3 times what it is worth (and what it cost me) to replace.