Which is more promising, CNC lathe or CNC milling machine? Why?

Might as well learn milling machine. First of all, you must ensure that you must learn well. If you don't learn well, no one wants it or the salary is low. But if you learn well, you will be well paid and very popular.

I study milling, and I heard from job seekers that some companies just said that as long as you have good skills, you can raise your salary yourself, as long as it is not too outrageous.

First of all, I suggest you understand both. If the conditions are insufficient, learn milling first.

Because it is easy to learn contact milling, but it is difficult to learn contact milling.

The future development direction of machine tools is integration and modularization. In other words, you can do everything in one bed, which requires you to know them as well as be familiar with them. Most beds are imported, which are quite expensive and are not allowed to be used.