Perhaps this is a semantics issue. I use the word entitled to mean that you have been found eligible to receive benefits. You have been denied.

If a person is denied SSDI benefits, that means they are not legally entitled to those benefits since the agency that has the responsibility of making those decisions has said so. Until you have an approval, you are not entitled to benefits. I do understand that you disagree with the decision for a variety of reasons, and that is why there is an appeal process.

In a criminal case, the burden of proving guilt is on the prosecution; the person charged with the crime just has to establish reasonable doubt. In SSDI, the burden of proving that you meet the criteria is on you. The Social Security Administration assumes you are NOT disabled until proven. It can't work the other way with SSA - SSA does not assume that everyone who applies is necessarily disabled and SSA has to prove otherwise. The criminal court assumes you are innocent until proven guilty.

Now I am confused about your statements about Medicare at age 65 and retirement benefits at age 62. If you don't have 40 quarters, which is 10 years of work in your lifetime, you won't get retirement benefits. You also won't get Part A Medicare without paying hefty premiums. There can be a higher premium for Part B for people with substantial sources of other taxable income based on tax return data; or if you apply for it after age 65; otherwise, everyone pays the same amount. So if you don't have 40 quarters at age 60, your date last insured for SSDI has to be decades ago. And I can see why it is hard to gather medical evidence before your date last insured.