I did retirement home training and used to think it was a sweet job. Then I got in the business and underestimated how demoralizing it was as they give you the easy elders in training while the others make you, or at least me, really think of the fact the job just amounts to an unkarmic freebie.
Weight training can be super dangerous if you don’t know what you’re doing, you can easily do significant damage to your back or knees doing fairly basic exercises like a deadlift or squat incorrectly.
Especially as weight training is increasingly encouraged for the elderly, personal training seems a fairly reasonable job. Admittedly, like any other job, there are folks who provide little to no value (think of the teachers just waiting to collect their pensions) but that’s not to say it can’t be a super useful industry.