Totally different situation, as my game is more social and lower stakes, but find that my games are held together by a core group and others float in and out. Life conflicts seem to be the biggest challenge as all the players are also fathers.
Pretty similar to my dynamic, actually...
I have one player who always arrives about 2.5-3 hours hours late after making dinner / putting his kids to bed. This is perfect for the game, because usually someone has busted or is about to dust off their last bullet by then—the late arrival fills the empty seat. But this fall he is coaching sports on Thursdays, including some travel, so he is out until winter. Good for him, bad for the game.
Other life stuff is always coming at people, just as it looks like I’ve solidified the player pool to the point of having a a wait list.
I have one player who is undergoing a major medical treatment this fall and will be in quarantine (due to a suppressed immune system) until at least January. That’s assuming everything goes according to plan.
Another who has been in and out of the hospital with heart issues and is taking a break from everything except trying to regain his health. He also had a bad garage fire this summer, after a cordless drill battery caught on fire. Talk about runbad.
A third — my most regular player — whose cancer cropped back up after a decade of remission. So far he is still playing almost every game, even sometimes on days he got chemo... But there is always a chance he has to drop out for a while or entirely.
A fourth former super-reg who has lapsed for more than a year due to financial issues. His business was going great, but he badly overextended himself (irrational exuberance, as iirc Alan Greenspan used to say) and now is digging himself back out.
A fifth and a sixth who both would be more regular, but their work is constantly taking them on cross-country trips. Instead of being here 80% of the time, they each make about 1/4-1/3rd of games.
A seventh who dropped out of poker entirely when she got pregnant. Maybe I should hand out out free condoms to my regs, amirite?
I could go on, but the point is that while many people care passionately about poker, it is always an option they can set aside for a time, or even permanently, when life comes at them. No one except true degens feel they “have to” play, much as we like it... So poker is often the first thing to get cast aside in a crunch.
Meanwhile poker by its nature does not require continuity for players—they can come and go as they like, unless your game is a league of some sort demanding steady attendance. I try to create incentives for regular play but there are limits to what can be done for a cash game.