I would argue that Muslims are, by default, required by their religion to make the hajj.

No it does not. The verse is quite clear: {وَلِلَّهِ عَلَى النَّاسِ حِجُّ الْبَيْتِ مَنِ اسْتَطَاعَ إِلَيْهِ سَبِيلًا} {And for God is the duty of the people to perform the Hajj to the House, whoever is able to make a way to it} emphasis mine. If someone knows they can't: sick, poor, etc... the verse says basically don't go.

While I wouldn’t call myself an Islamic scholar, I would say I do know a bit about it.

Do you know that in certain cases Hajj is haram? Possibly risking your life is one reason why many have prohibited it.

Not the worst outcome for whom? People are dead. I’ll bet there’s at least one child, sibling, or parent who isn’t terribly comforted by the idea that their loved one is a martyr.

For the faithful it is not. I don't know what to say more than this. They could have not performed hajj but they chose to oblige themselves.

would argue that Muslims are, by default, required by their religion to make the hajj. You make it sound as if it's opt in, but their religion mandates it with some exceptions.

Nah dude, the vast majority of Muslims never go to mecca. It's not a mandate anyone enforces but yourself. I think only like 9% of Muslims ever actually get to make the trip.