I feel like this is the reason so many pilots are engaged in side hustles. In my case it was driven by not only boredom, but the 'have a plan B' that all of the older, grayer pilots always warn you about.
Saying that the airlines are generally more secure jobs doesn't fit well with history, as the airlines are more volatile industries than most. They are highly impacted by economic downturns and oil prices and if you're out of work, there are few ways to transfer skills, as I discovered first-hand.