A tritone interval by itself (only 2 notes sounding) sounds quite dissonant to me. But in the context of the dominant 7th chord, the only note dissonant with t

A tritone interval by itself (only 2 notes sounding) sounds quite dissonant to me. But in the context of the dominant 7th chord, the only note dissonant with the bass is the 7th. The tritone itself is not so prominent since it occurs between two non-bass notes.