It makes sense. Tennis is such an individual sport, it's rare for players to get a chance to play in a team environment, even rarer to play as a team with people from other countries. Imagine if we could see an Alcaraz/Sinner doubles some year? Golfers take Ryder Cup very seriously, it's a prestigious event and they all want to be a part of it. Haters can hate all they want but Laver Cup plays to sell out crowds every year including this year in San Francisco. All 5 sessions sold out in the 17,000 seat arena per the Athletic, with prime seats reselling up to $1,000 or more. If you average out the tickets to $350 each just the ticket receipts is close to $30m, plus sponsorships (all those corporate signs inside the arena), TV rights, this is a profitable venture.
Players like the team atmosphere but I'm sure they also love the paycheck. Each player gets an appearance fee based on ranking and popularity. The winning team member each gets $250K. Losing team members only get appearance fee. Wouldn't surprise me if Alcaraz gets $1M in appearance fee. But many players also get appearance fee in ATP events especially the 500s and 250s.
So far I've seen the Alcaraz/Mensik doubles, Rune-Cerundulo, Alcaraz-Frits and the Rune/Ruud doubles, they are all high quality and very entertaining. I'm planning to watch all 4 matches today.