The first character starts by saying their view on a situation, the second then replies with an opinion that is viewed as ridiculous and unbelievable by the first. This first character then replies:
In the subtitles this is translated as:
I have issues, but you're just as bad.
While I understand the translation for the second half, 「ボクも大概だ」 doesn't seem to make sense.「大概」 meaning 'generally' or 'mostly', is it akin to the phrase 'I'm not all there' in English?