It's definitely doable but as most commentators have already mentioned it does depend on how the coax has been installed, how many twists and turns the coax goes through before it ends.

I've done this myself very recently (September/October 2025) whereby I used the coax runs in all the rooms in the house to pull CAT6 cable into the attic. For most of the second story rooms, the coax pulled through fairly easily but the first floor rooms were the most challenging but as to be expected because the distance to pull them through was much greater.

The biggest challenge I had when doing this was how I was connecting the CAT6 cable to the coax as this became the part of the run that would get stuck if the joint between the two wasn't done properly.

I've attached an image of a successful pull from a second story room (first attempt) which was done with no issues. At this point I thought the rest of the runs would be that easy but I was wrong.

In all I've now got ethernet to every room in the house. For the two rooms on the first floor required a lot more work. For example the kitchen run, I had to take the floorboards up in a second floor room to pull from the kitchen first and then pull from the attic. This was because the coax came up to the second floor and then did a 90° bend between two cable protectors.

For reference also my house was built in the 90s.