You’ve been on borrowed time for the last 5 years and you’re also being given a bit of erroneous information.
When the timing belt is changed one always changes the belt tensioners, water pump, and any other belts that need it; no matter if it’s accessory belts, balance shaft belts, etc.
Failure to do that can easily leave you on the side of the road 2 weeks after the timing belt replacement with the options of having the car towed and repeating the job or having it towed and finding out the engine is destroyed (depending on make of car and engine).
A DIYer at home can perform a halfway repair and let the chips fall where they may. A competent mechanic should refuse to replace a timing belt only. It’s begging for trouble.
The only way to avoid this particular kind of repair is to do your homework before buying a car and spending your money on a car that uses a chain instead of a belt.