Sure, its's free*.

- except the cost of materials and gas to drive to the hardware store, which you'll likely do twice or thrice as you realize you bought the wrong thing or need some other specific tool, that you'll use one time a year or less

- except the cost of your own time away from personal projects and family

- except the cost of hiring a plumber afterwards to professionally fix the problem you caused by DIY'ing it without the knowledge and experience that a professional brings

The fact that you ask such a question shows how different people are. It almost reads like a joke to me.

I have zero interest to learn about plumbing and I would pay a professional even if I could do it myself to avoid any doubts or fears of messing it up.