Why is 2 bit an insult?

Excuse me, could you please elaborate on why the phrase "2 bits" is considered an insult? I've heard it used in some contexts, but I'm not entirely clear on the historical or cultural significance behind it. Is it rooted in a particular era or region? And what emotions or connotations does it typically evoke when used as an insult? I'm genuinely curious to understand the full context behind this phrase.