The subject of the article, and fellow social media participants, are hedging a bet that manual trade jobs will be safe forever, at the cost of a salary cut and inflicting physical damage to the body. All to do a trade that perhaps doesn't even interest them that much. Insecurity, maybe even arrogance, is driving these people outside of the white collar workforce and I think they will get burned for their decision in the long run. Because there really is no guarantee that these physical jobs will be safe.
The other subtext is that white collars should take a salary cut to work in a different field. And who absorbs the difference in salary that is no longer being paid out? No one that is the subject of this article.