Do I beleive online sites are rigged? No.
One thing to keep in mind is that a poker room does not make lots of money off you losing your chips all at once (when playing cash games). In those games the money is made over time by collecting the rake. It doesn't matter who the rake is coming from. And the benefit to the room would be to NOT eliminate players because once the money is in someone else's stack they can't make money in the form of both players building rake. so if they were going to be rigged they would be rigged so the smaller stack would win most of the time.
In tournaments, the benefit to the poker room would be for players to exit the tournament as quickly as possible so that they will play in another tournament. If a site was rigged, then it would favor the poker room to kick out people who had lots of money in their
bankroll because they are the ones who would be playing in a new tournament.
Do I believe sites are rigged, no. But if they were rigged this is how they would be rigged.
Although, there is the theory of no beneficiary rigging. This is where the RNG is programmed to hand out good hand vs. great hand a lot. This would encourage players to increase their betting without picking any specific player to favor.
If you must consider a game rigged, don't think it's rigged against you specifically, think of it as being rigged against everyone and you just happen to end up on the short end for whatever reason.