Is it worth buying a used 2010 mbp?

Just to add my "2 cents" to what has already been provided, and by experience with owning one, the 2010 MacBook Pros do have one notable "Achilles Heel" and that is with their graphics processors. These models come with two of them. One is integrated and the other discrete. Either can become faulty and typically presents themselves with display issues ... like white areas on the screen appearing with colored lines. There are some workarounds, but no real solutions.

I suggest that you ask the seller if you can use this notebook for a week and see if it comes up with any display issues. You can also run the Apple Hardware Test to see if it finds any errors.

How to use Apple Hardware Test on your Mac - Apple Support

It depends what you want to do with 2010 MBP.

Same as is it worth buying a second hand car?

The MacBook Pro (13 inch, Mid 2010) model discontinued in 2011

If you are buying it, make sure the seller did this: What to do before you sell, give away, or trade in your Mac - Apple Support

What are you going to use it for? That's the question.

Vintage and obsolete products - Apple Support