The Rambam praises those who learn all day and don’t have jobs, as the elite “Shevet Levi” of our days. Clearly, even if working is endorsed, it is inferior to those who learn.
As an aside, the Halachah is that you are nowadays allowed to live off Tzedakah to learn (see the Ramah and Shach in Hilchos Talmud Torah.)
If learning in Kollel is against the Chazals about Melachah and Derech Eretz, then so is being a Rebbi or a Rav. See the Rama YD 246:6. He brings your Chazals and says that therefore nobody can be a paid Rebbi or a Rav either, since he relies on the congregation. But then he brings dissenting opinions, and rules that the custom is that Torah scholars do benefit from their learning, by support from the community.
The Rama then says it is a Midas Chasidus – praiseworthy – for someone who can become a Gadol B’Torah and make an independent living, but continues that not everyone is capable of this. It is clear that he is saying that if you have a choice between becoming a Godol B’Torah or making a living, becoming a Godol B’Torah comes first.
The standard of livelihood required is bare minimum. “Kach hi darkah shel torah – pas b’melach tochal etc.” — Bread salt and water – if you have that, you have parnasah. The Rambam writes that a typical Baal Habayis works 3 hours a day and learns 8.
See, its very nice to make an independent living, but it is more important to become a Godol B’Torah. If you cant have both, then Torah is the right choice. Whatever advantages there is in making money, they do not come close to those of becoming a great Torah scholar.