כִּ֤י דְבַר־יְהוָה֙ בָּזָ֔ה וְאֶת־מִצְוָת֖וֹ הֵפַ֑ר הִכָּרֵ֧ת ׀ תִּכָּרֵ֛ת הַנֶּ֥פֶשׁ הַהִ֖וא עֲוֺנָ֥ה בָֽהּ׃ (פ)
그런 사람은 여호와의 말씀을 멸시하고 그 명령을 파괴하였은즉 그 죄악이 자기에게로 돌아가서 온전히 끊쳐지리라
Tanya
And all the more so, in a fortiori inference, one who stays idle while being able to perform some positive mitzvah and does not, such as one who is able to engage with Torah and does not, about that person our sages used the verse "the word of Hashem etc, cut-off certainly cut-off etc" (Ex. 15:31) (see Sanhedrin 90b) and it is obvious that one is called wicked - even more wicked than one who transgressed a rabbinic prohibition!