I'm not so sure you necessarily develop resistance. I know someone who has been bitten so many times by rattlesnakes (job hazard) that they can't administer antivenom anymore. He was advised that if he was bitten again he would probably die.Of course you could do what I accidentally did with wasp stings. Be very unlucky and keep getting stung until your body builds up a resistance…
Or you could get a doctor to do it in a safe environment with tiny doses but what’s the fun in that?!