Here is an American example, Fox suspensions. Fox is one of the main producers of bicycle suspensions. Great products, but check their service intervals for a fork [0], 125 hours.

Now if you practice mountainbike you may ride your bike 1 to 5 times a week. Let's say you only ride once a week for 4 hours: 125 / 4 = 31, you would need to service your fork every 31 weeks. Add some few more rides and you have to service the fork twice a year.

Each service easily costs $150 if done by a bike shop. If you do it yourself (plenty of tutorials on youtube), you need expensive special tools, oil, special grease and spare o-rings and seals easily costs 30-40$ for every service. And you have to properly dispose the old oil.

[0] https://tech.ridefox.com/bike/owners-manuals/2979/fork--2025...