Enough hours that if you applied them to a job you could buy a decent house. Do you regret it at all?

There are 8,736 hours in a year.

How is this possible? When do you play, for how long?

The game has been on steam since 2016. That's a bit more than 1000 hours a year, which isn't as much as you think

The equivalent of 50% full time job (37.5 hours 52 weeks a year) or 2hr 45mins a day every day of the year

My issue with factorio is that I'll not play it for a few days and then I'll just lose all of a Saturday to it

40 hours a week is 2000 hours a year.

Steam keeps counting "time played" while your PC is in Sleep mode with a game still open. Factorio is quite small, resource-wise, so keeping it open in the background is convenient.

Not saying this is the only possible explanation for 7000 hours. It's just something I noticed when my "time played" was way higher than what is plausible.