I don't care about the morality aspect. I lived in Las Vegas for 24 years as a sports bettor. Most people should not gamble because they are addicted to decisions. That is the advantage for the house, not the juice. The house makes no decisions whatsoever, after the game is set forward. But the gambler is awash in subjective decisions, essentially inventing ways to lose. It is the reason the best sportsbook manager I ever worked for said his dream scenario was for every gambler to watch every sport all day every day. With that much information he knew they had no chance because they would totally lose sight of the wide scope in favor of overreacting to the last thing they saw.
Sports betting does have the equivalent of index funds but it's up to the gambler to find them. They are logical systems that grind out advantage based on historical trends. But instead of set and forget you have to identify the games that fit the systems and continuously invest. It worked very well for me. I took the winning and applied to the stock market beginning in late 2008. That timing was coincidental, not strategic. My mom caught MRSA and died in December 2008. I had to move back to Florida to help my elderly dad. My best system with the market has been to use index funds but handicap the sectors. With only 10 or 12 sectors it seemed possible to weight that many variables, as opposed to thousands and thousands of individual stock or mutual funds or ETFs. I decided I wanted to be high in technology and health care. The market is something like 24% technology while I've been at 37%. I realize that sector doesn't have to continue to overperform but the strategy has served me well. My logic is that I don't care about the occasional down years for technology and health care. The big years will more than make up for it.