Celebrating space mission failures for any reason is a terrible look.
This is a cultural difference, try to take a step back from your own preconceived cultural norms. What's considered confidence in Israel would qualify as hubris in American culture - there's much less value placed on being humble or soft-spoken in Israeli culture. I make no judgements about if this is better/worse but I certainly wouldn't dream of relishing in their failure even if I perceived them as "cocky".