Good food and free t-shirts.

Teams are supposed to supply 2 volunteers; sometimes college alumni are good for this. There's also been quite a few off-seasons up here* even before districts, which helps keep people engaged. 1640 alone has volunteer(s) for at least: Monty Madness, MidKnight Mayhem, girlPOWER, Duel on the Delaware, Brunswick Eruption and Ramp Riot, plus Battle 'o Baltimore (MD) and Lewis Blitz (NY).
But in all honesty, a good part of the reason FiM and MAR were the first to transition was
because we had strong volunteer bases. If we're taxing bases this size, I don't envy regions that self-classify as having a small volunteer base.
*It's interesting, MAR has 5 off-seasons in like 35K miČ (NJ+DE+.5PA): by my reckoning the highest in the world. NE is 2nd with 6 in 72K; PNW is 3 in 170K. You can actually see their "bubbles" on the
calendar:
ME: SPIRIT
NH: Merrimack, Rage
MA: MSHSL, Beantown
CT: Wolcott
NY: Ruckus, Lewis
PA: girlPOWER, Riot
NJ: Monty, MidKnight, Brunswick
<<I think only MN has more, and it's 10x the size (albeit 3.5M fewer people)
MD: BoB
VA: Rumble
NC: THOR
SC: SCRIW
FL: Panther
LA: Stick
TX: Roundup, reMix
AR: Ozark
MO: Cow Town
IL: River
IN: Champs, IRI
OH: Connect
MI: MARC
MN: Detroit, Invt'l, Rendezvous, Champs
OR: Seattle, Generation, Rollout
CA: CalGames, Classic
Aust: DDU