I mean the actual medicine part. When I think about it, there are still no cures for the major things that ail us (e.g. cancer, etc.). China cured that one guy from his diabetes, but I haven't heard anything beyond that.
The "promise" of stem cell technology from 20 years ago still hasn't amounted to anything that your average person can get (and there are all sorts of shady overseas places that give ppl "stem cell" injections, but honestly we should have figured out that shit by now).
If you tear a ligament/tendon, guess what, that shit will never heal back to 100%, and the "oh just rest and do physical therapy" shit is annoying because you're only really working around the problem and not solving it.
On top of that, as you get older it's harder for your body to heal from injuries, sickness, etc. and I've yet to see any legit progress on anti-aging. If your heart is damaged or arteries clogged, I don't see any way to reverse it.
And after covid, it's all been fucked. How many people have long covid and the medical establishment just throws it's hands up 
basically treating an entire segment of the population as though it was a bad crop yield ("I guess there's always the next batch!!).
And doctors themselves are often the biggest dipshits out there. They are high off their own supply because they're "smart" and lack the empathy to actually listen to patients. Either they're older conservative types or younger lib dipshits. And there are so many horror stories about nurses that talk shit about patients. It's just dismal.
The common reply is that "biology is hard" but honestly that's a WEAK excuse. So many advances were made in the past, and there are so many more to be made. An actual concerted international effort, unhindered by profit motives and fucking insurance, hospital, pharmaceutical industries, etc. would almost certainly yield results. I mean look at Cuba coming up with a lung cancer vaccine and curing HIV in an infant. Look at China curing diabetes in that one guy. These advances are possible, but honestly they aren't coming fast enough. If you're suffering from a terrible disease/ailment, the "promise" of a new drug that still may be 10 years away is just terrible.
So even if we had 100% socialism now with free healthcare, there are still so many things that need to be addressed. I can't help but think that had the Soviet Union not fallen, we would have had cures for many things. Hopefully 
can do something about this, but overall I'm still super bummed that the future we dreamed has not materialized.
I feel slightly angry with you punching on the people working in healthcare that actually provide the care.
Nurses, but also doctors are working nonstop to keep the patients and also the system running as good as possible within the constraints that they're given. They cannot afford the time to try and change the broader political environment in which they have to operate. Doing so would cost lives. I'm not American, but German and I know a few doctors personally. They're pretty decent and even very left leaning people. The shit, human misery caused by a broken system, privatization/monetization of healthcare they have to deal with necessitates a certain dark humor, fatalism or cynicism to just stay sane enough to continue doing it. We as a society have failed to address this problem - the conditions that we put on them - and their only option is to develop a defense mechanism. You may not like it, but this defense mechanism against all this shit is better than the alternative - them all giving up and quitting. At least short time. Maybe the only way to fix it would be a mass walk-off/strike that actually causes a lot of deaths for us (society) to actually wake up and fix it. Unfortunately the majority only has to experience health care in exceptional circumstances. Otherwise it's pretty invisible to us. We only know about the overworked nurse or the uninterested uncaring doctor. We don't know the rest of the story - all the other patients they have to deal with at the same time. The bad news that they have to bring and the angry responses they get a thousandfold from unlucky patients, the treatment they have to deny because of asshole CEOs of insurance firms and the politicians who enable them (that we as a society don't remove with some pitchforks). We only see the end product of a person that has been molded by this broken system and we get angry at them. But they are not the problem. Doctors don't start their job wanting to be this cynic version of them. That's just the shit they have to deal, because we as a society don't help them that makes them so.
And yes they get tons of money and all that (the doctors), but I'm not convinced that they get to enjoy it that much.
I'll push back a bit on doctors being left-leaning. In every country that has tried to socialize healthcare, doctors have organized and aligned against it. Here's an article about it: https://www.vox.com/policy-and-politics/2019/3/29/18265530/medicare-canada-saskatchewan-doctor-strike
If you want to learn more about the formation of Canada's single-payer healthcare system and how it was influenced by the Soviet model, there's a good book called Radical Medicine.