This is not a DIY job. The skill and tools required are of a cabinetmaker. Unless you are already a woodworker, you wouldn't learn the trade if you took two months, or even two years off work. Not to mention the thousands of dollars in tools you would need.

Did you install your own laminate flooring? That would be a good project to tackle for a handy DIY'er.

The stairs are in a different league.

I did the laminate myself. Why does it require the skills of a cabinetmaker? The stringers are already made, and the treads are pre-mitered.

It requires the tools of a cabinetmaker, mainly a table saw, router, and mitre saw. And a couple of pneumatic nailers.

The skill is more of a safety requirement. Portable table saws are extremely dangerous for a novice.

An person's standards of craftmanship are completely subjective. You may be perfectly capable of producing finish carpentry to your own satisfaction.

Go ahead and remove the carpeting yourself, but it's a false economy to try to remodel stairs yourself.

The hard part is getting the newel post and railings set firmly.

That alone is worth hiring a pro to do, because if you mess it up, you have a wobbly, unsafe stairs. And you have one chance to get it right. Drill wrong and you replace a bunch of stuff and try again.

It's a medium-hard DIY job in new construction, because you have better access to the places you need to access.

$6k isn't a bad price for the work involved in maple.

You can take a week off but it's going to take every bit of that time to do the job.

Will you save enough from what you earn to justify it?

No need to remove the plywood if you don't want to but what's to keep it from squeaking? Enough goo should keep what you put on top quite.

You can see by the overcuts that you've got very rough cut stairs.

If you DIY you've got a lot of work ahead of you.

Best of luck.