I started flying gliders a few years ago, currently the holder of a BGA Bronze plus Cross Country Endorsement.
Firstly, given you're 16, you will at some point likely be looking for a career or further studies at some point in the near future. Gliding can really help with the life experience side of things, particularly if you apply for anything safety critical, it'll give you quite a bit to talk about at interviews. If you do apply to the airlines in a couple of years for any mentored/funded programmes, you'll likely get asked about how you can demonstrate your interest in aviation. Gliding gives you a good example of that. It's the same with scholarships or the UAS if you go to uni.
Additionally, being a member of a gliding club can be useful post-PPL since you're going to be in a much stronger position to gain a position as one of the volunteer tug-pilots. Some clubs have seasonal tuggies who fly to hour build, you could probably get a couple of hundred hours over a summer, which either gives you extra hours on the modular side, or reduces your hour-building costs.
It is possible after a couple of years (depending on how much you fly) to become an instructor, if you were to look for an instructing job after doing a modular fATPL, I would think that the experience of having instructed previously would put you in a good position for an instructing gig.
Many gliding clubs operate a "cadet scheme", where being 16-21 and in full time education will get you massively susbsidised/free flying.
It also gives you the opportunity to network, aviation can be a small world and knowing someone who knows someone can, from what I hear, be useful from time-to-time.