Can’t I engage in self-development because of prayers missed without a valid excuse?

The authoritative scholar of the Shafi'i madhhab, Ibn Hajar al-Haytami, writes in his book “Tuhfat al-Muhtaj” the following: > “A person who must make up for prayers missed without a valid excuse is not permitted to spend their free time on anything except making up those prayers. It is not even permitted to spend time on voluntary (sunnah) acts. The exception to this is the time one is forced to spend on sleep and the like, earning a livelihood to provide for those they are obligated to support, or other obligatory duties if the time allotted for them is running out and there is a risk of missing them.” I want to spend a lot of my free time on self-development, for example, studying English on my own etc., but I have 2600 missed prayers without a valid reason, in this case, can't I really develop myself, relax, but I must spend all my free time filling them up? (I adhere to the Shafi'i mazhab)