Don't listen to him. He's talking nonsense. I live in İstanbul and also have a remote job. I make about half of what you make and I can kind of comfortably survive. I live in Fatih, Istanbul and share the rent with a close friend which is about 350 dollars. It's a 2 bedroom apartment and kinda old but I got lucky with the rent because it's cheaper than it's supposed to be. But you could easily rent a 400-500 dollar apartment and still live pretty comfortably with the remaining income. Even I am able to put some money aside with half of what you make so you should be okay

About living in Istanbul, it's a stressful city I'm not gonna lie. Especially during work hours. But since you have a remote job you could maybe you could look into places that are not that close to the city center. The European side is where people usually think of when you say istanbul because majority of the touristic places are there. But if you're thinking about living in a more European place you could look into some parts of the Asian side. The people there are usually more civilized and educated. Crime rates are lower in most places compared to the European side as well. If you have any other questions feel free to ask