Gamblers are having fun and most of them are making a profit, even if there is a house edge, the house edge is very important so casinos will not go out of business, this is their guaranty that they will stay to serve gamblers it's a necessary evil but gamblers are ok with it because they can still win while having fun.
If you really see it that way you should read again why there is a House Edge and what effects it has 
Because of the House Edge, a player cannot be profitable in the long run, let alone "most of them". If this were the case, the House Edge would not work and the casino would go bankrupt in no time
Statistically, this is not totally true
A thoroughly devised and implemented martingale strategy allows to override the house edge advantage, and if all players at a casino would utilize it, the casino would in fact be ruined in "no time". It doesn't happen for the simple reason every and each player is for themselves. However, if the players colluded, their profits combined would suffice to kick the casino out of business even if individual profits would still be tiny. Profits are profits, and gamblers' profits are casino's losses, no matter how you look at it
@coin-investor you’re partially right because when I used to play slots games at online casinos, I used to enjoy them and I didn’t really care for the house edge part.
However at the end of the day when I used to look at my balance to see if I have made sufficient profits, I used to get a rude shock because despite winning several times, I yet didn’t make any profits and that’s when I truly began to understood why house edge matters to the casino.
Furthermore it doesn’t stop me from playing because I strongly feel that the casinos deserves to keep it to maintain their profitability, and @deisik I don’t think what you have mentioned here has ever taken place, and I don’t expect it’ll ever happen unless someone has a hidden agenda against the casino.
Quote
The House Edge is a term used to describe the mathematical advantage that the gambling game, and therefore the commercial gambling venue, has over you as you play over time. This advantage results in an assured percentage return to the venue over time, and for you an assured percentage loss of what you bet.
It’s important that people don’t think that they can win, because you can’t win in gambling. You can win for a little while but you can’t win in the long run.” – Michael Piggot, spokesman for Tabcorp, one of Australia’s largest betting agencies, on the National 9 News, September 2005.
Source:
https://knowyourodds.net.au/house-edge/