It’s not wrong.
Pirkei Avos, 2:2
Rabban Gamliel ben Rabbi Yehudah HaNassi would say: Beautiful is the study of Torah with the way of the world, for the toil of them both causes sin to be forgotten. Ultimately, all Torah study that is not accompanied with work is destined to cease and to cause sin.
Rambam Hilchos Talmud Torah 3:10
Anyone who decides to be engaged in Torah [study] and not to work, and will be supported by Tzedaqa – this person desecrates God’s name – Chillel es Hashem
And of course, we are commanded to be koveyah itim for studying Torah. The mashmo’us of being koveah time is that much of one’s time is not engaged in Torah, but in other pursuits, such as work, which are sanctioned and expected by halocho.
This is not to say that those who have a skill and talent beyond the norm shouldn’t be learning full time – aderaba, they should be fully supported. But it does indicate that at least according to Rabban Gamliel and according to Rambam, it should not be the norm for every bochur.