If I have significant savings and investments, given the extremely high cost of CI premiums at older ages, would it make more sense to self-insure instead?

Hospitalization plans covers the uncertain medical costs.

The objective of critical illness is to cover lost income during recovery. As you shift towards retirement, your portfolio should give you income, regardless of your activity at work.

I wouldn't classify it as "self-insure". That is an incorrect angle. Rather, you should be focusing on passive income in retirement while protecting medical cost uncertainty with hospitalization and medical insurance.

Death insurance during retirement is part of the estate and legacy planning - to leave bequeaths towards surviving spouse, children, or charity.​​​

Depends how old you are right now. if you are like 60 to 70 then just self insure and make sure u got your hospitalisation coverage setup.

Self insured at your old age is a good goal to work towards if you are young now. But between now till then. using savings and investments to pay off medical bills will not only cause you to lose your money, but also the time, sacrifices and effort you put into your savings and investment.

if something happens at a bad timing and forces you to sell all your investment at a 50% loss, how would you respond to that? If you dun want to think about it, then Term or Limited pay Ci Coverage could be a good idea.