We have six leptons and six quarks. Yet most of what we see around us is made of only neutrons, protons and electrons. For $\mu^-$ and $\tau^-$, I think the reason is that these are unstable particles and quickly decays into $e^-$. But I have the following doubts.
Why do neutrinos, $\nu_e,\nu_\mu$ and $\nu_\tau$ do not form ordinary matter?
We do know about certain baryons and mesons containing $s$ quark in addition to $u$ and $d$. Are they all unstable? Why?
Is any bound state containing $c,b$ or $t$ quark unstable?