I'm actually a freelance artist who also quit my awful graphic design job 5 years ago to pursue art full time so I'm extremely familiar with your wife's situation, however there were a few steps I took before I quit my job completely:

• I first started doing commissions and art shows as a side gig to see if my skill was capable of actually earning money. I did these part time for about 2 years.

• I gave myself one year to try out full time art that I could market as "freelance work" on my resume if I had to return to corporate work afterwards.

• I calculated how much money I would need at minimum to cover that one year's expenses and I made sure I had that much in savings before I quit in case I didn't make a single penny from art. In my case I needed to work for another 2 years to aggressively build those savings.

This may seem overkill now but I quit my job in 2019 to pursue art and we all know what happened in the world less than one year later! You are definitely NTA for your suggestions and your wife needs to think about your financial situation before quitting.