human body adapts to everything.
same way your eyes adapt to darkness (nightvision)
same way your body adapts to benzos (valium, Xanax, ect..).. .5mg Xanax will put me to sleep in 30mins if I take one tonight, but if I take them everyday, eventually I'd be able to take a full bar (2mg) a few times a day. not that I've ever done that.. benzo's have no appeal to me.
back when I drank daily.. I'd drink a liter of vodka before 1-2pm, and another liter the rest of the day/night, and nobody knew I drank.. never 'passed out' or had blackouts or crashed my car or anything. body will adapt for a while, but then something's gotta give.. in my case it was pancreatitis, twice. first time was a 10day stay in the hospital getting 2mg dilaludid every few hours.... went many years without drinking anything, now i'll drink a beer (with sushi or burger) or 1 glass of wine (with pasta) maybe once every 6-8 weeks, if that. if I have more than 1.. like 1.5, it feels like too much and I'm regretting that 1/2 half.
body adapts to cold, move from California to Minnesota. after the first month of the first winter, you're used to it.
body adapts to heat... move from Minnesota to death valley. same thing..
body adapts to spicy food.. 3yr old southeast Asian kids eating thai/lao Pappaya Salad with 3 peppers is like nothing, whereas I'm freakin dying with 1 pepper.