It's OK to be uncertain about things. As a scientist it's essential to state one's uncertainty, in fact.

This can be a good antidote to claims of "fraud." Unfortunately it tends to conflict with the American culture of "entrepreneurial machismo", where everyday is "crushing it" and everything is going "to the moon!"

Ideas need to be challenged, attacked, and sometimes even killed so their parts can be digested to form better ideas. Life feeds on life.