IMO yes a tolerance will likely develop. Like any drug you will have to "use more to get high". This means you'll have to push harder longer to get high. This will likely take a few years though. That was my experience.

One thing to consider is you are big and are trying harder to push your body now than you will in a year, after you've lost (likely a lot of) weight. To achieve the same high you will have to use extra effort because you won't have to try as hard to push a smaller mass.

After 40 years of hard riding I can't say I experience endorphin highs, but I still feel great after a ride. I haven't been to a doctor in 40 years either.

Keeping pushing and you should be enjoying your high for a while.