There are expats living on their government retirement pensions. They may or may not have savings. It isn’t a problem unless they suffer a serious accident or illness that prevents them returning to their home countries for treatment.
You’ve done the right thing. Go to A/E as soon as possible. Not expensive in Thailand. You should be able to claim under your travel insurance (if applicable).
Possibly the agent was only trying to be helpful in anticipating that an immigration officer could see an opportunity to ask for a tip/bribe? Alternatively, the agent could be touting for business if obtaining replacement/renewed passports are part of their service?
Immigration Officer's seem to be 'tightening up' in general, requesting photocopies of forms and documents they hadn't previously asked for. What they are asking from you sounds normal.