In my experience, "provably fair" has become just another buzzword, and for most sites all it means is that you can find an encrypted hash corresponding to the result of the roll when you investigate.
I doubt your experience because Provably fair is an algorithm and not just an encrypted hash. Are you sure you know how to verify the bets using the server seed and the client seed? It does not correspond to the result of the roll but how the roll is made.
I believe only for a very few number of exceptional sites is the algorithm independently random, and the website is truly blind to the outcome of all bets...
We have a number of cryptography enthusiasts in this forum and believe me they are having a sane mind enough to look at every new site that comes up and verify the bets made there to be truly random and not rigged. Previously they helped in shutting out some scammer sites who cheated their players and the ones who are in this forum and highly popular were found to be fair.
What you are suffering from is Gamblers Fallacy and I suggest you to verify the bets yourself to put your mind at ease and that you lost the money because of your own greed and not because the site cheated you.
you are making too many unfounded assumptions as if you are personally invested in protecting the interests of gambling sites, interesting
is there an archive available for all gambling sites that are promoted on this forum where you can go and verify each and individual historical bet if you choose to ?.. I sincerely doubt that, please correct me if that's the case.
Then, is it possible for a site to be "provably fair" in some cases or let's say in the beginning, but to subvert its algorithm (or seeds) for some of the bets that really matter down the line, say when they notice the user is using Auto Bet and would be very unlikely to check most of those ?..
OR, is it possible for a site to give different weightings to certain outcomes from what is mathematically expected, let's say achieving a rolling of above 97 out of 100 becomes not really 3%, but in fact it's more like 0.03% during certain cases...
For the latter example, it's already a documented statistic that one of the most popular sites (which also has a massive thread here) is doing exactly that for many years, and yet you can still see the buzzword "provably fair" everywhere on their website, just to give you one case that refutes your propaganda scented response
...
*EDIT: ps.: unlike what you think, I hardly ever use these gambling sites, and haven't investigated in depth these specific cases so I'm not going to name any names and leave room for doubt, but it can be reasonably deduced that these are very likely possibilities from the testimonies of a number of experts in building gambling websites (similar cases have been taken to court and proven there as well for example regarding the true "randomness" of some of the post popular online poker sites on the planet)...