"The Forwards win the match, the backs determine by how much."
An ancient Rugby truism... The game is won up front.
Think of primary, regular 'ol health insurance as the forward pack. And, consider supplemental excess plans as the backs.
If a prop falls on you, your primary health insurance will cover most of it, and your supplemental and/or excess insurance will close your overall out-of-pocket gap.
And, as also in Rugby, you can play without backs. England has done that for years.
But... BUT!!!! You cannot play without Forwards.
Simple kids: If you don't have primary health insurance, you shouldn't be on the pitch. If you can afford a supplemental plan over and above your primary, it could save you 100s and possibly 1000s in out-of-pocket costs.
Supplemental Excess plans DO NOT REPLACE PRIMARY HEALTH INSURANCE.
Remember, primary pays the hospital and docs directly. Supplemental and Excess plans pay you MONTHS afterwards. Supplemental and Excess are designed to help you recoup your costs, not pay off the hospital and MDs directly.
Plus, by playing without primary HI, you risk not just you, but your club, and potentially the league playing without health insurance.
And, it ain't that expensive for catastrophic coverage, or an HSA qualified plan. Get the supplement later.
Grow up, and be a Forward...
...you'll be the reason games are won.