This is really why I should donate to the "abroad" political arms. Both Republican AND Democrats agree on fixing Medicare, FBAR, etc. because citizens abroad are always an afterthought. I wouldn't mind being an afterthought if it wasn't sapping the biggest part of my paycheck while being utterly useless to me later in life or sucking out all of my time come tax season.
For a self-employed person Social Security is 12% on the first $147K of self-employment income, maxing out at $18,228/year. Medicare is 2.9% on the first $200K and 3.9% on income over $200K. So for a person making $200K+ the total of those is 12% + 3.9% = 15.9%.
For a person with a regular employer (you mentioned “paycheck” in your comment) the employer pays half of those taxes, so the employee portion is a little less than 8%.
That’s a significant chunk of income paid for Social Security and Medicare but I wouldn’t call it “the biggest part.”
Americans living abroad can collect Social Security, so that part is not necessarily utterly useless. Currently Medicare benefits only pay for treatment in the US, but in that case the percentage of income paying into that is no more than 2.35%.
If you have parents or relatives on Medicare you are actually funding them, think of it that way. Because of demographic changes America has a growing aged population and a shrinking population of young people. If you want to address that problem have more children.
If preparing and filing tazes is sucking out all your time come tax season maybe get a professional tax preparer to do it for you. I have been self-employed for over a decade, earning well over $150K/year, lived overseas more than half that time, and I never spent more than a couple of hours a year preparing and filing my taxes. Some people have more complex tax situations than others but most returns are not that complex if you keep your records and receipts organized.
It would be nice if US tax laws and Medicare and so on accommodated expats and nomads. That would likely benefit me. But I chose to live an unusual and minority lifestyle as a nomad, so I have to take the good with the bad. It's not worth my time, effort, or money to get involved with political lobbying on a niche issue that doesn't interest or concern the vast number of US citizens or the people in Congress who might make changes. The government will always have bigger and more pressing issues than unfair taxation of expats, and we will always be a tiny minority of constituents.
More than once I have encountered Americans who interpret my choice to live abroad as somehow "abandoning" my country, or running away from it. And most Americans don't know about taxes on expats/nomads, they assume that if I live in, say, Thailand I am not paying US income taxes. When I explain that Americans are taxed based on citizenship they are surprised -- why would an American who lives and works in the US know about that? Likewise Americans are usually not aware that getting a tourist visa to visit the US (for a foreigner) is often difficult and time-consuming -- they have never had to deal with USCIS. So that presents a political challenge: the expat/nomad lifestyle is not something the majority of Americans (or their elected representatives) understand or care much about.
Good luck with the uphill battle. There is an advocacy/lobbying organization for Americans living abroad:
https://www.americansabroad.org
Of course they ask for money. I choose not to get too involved with trying to reform the government or tax policies. It's a fact of life I can deal with, I have better things to give my attention to.
It's compounded though because of the other side: host country. They don't have a modern definition of "work" and so the rules put you in a gray zone so you can't or it would be prohibitively expensive to start a business and hire workers to meet the business requirements for visas (and sole-proprietorships not being allowed to foreign residence)--all for a self-employed remote work which only requires internet, a computer, and caffeine. If I could pay local taxes, then I could support the local community and subtract it from the US side. And I'd rather pay taxes to the local community. Applying for local citizenship is daunting and requires a long residency period and being on a wait list. Some countries like Estonia make it a lot easier.
It is a non-standard and often glamorized lifestyle, but it is filled with so many caveats.
On the other hand, finding the information you need to travel and live abroad is fairly easy these days. A little planning and setting your expectations smooths the process out. It’s not for everyone, and definitely gets presented as more glamorous and exciting than it sometimes turns out. A person who is unhappy, lonely, insecure, financially unstable, or operating from unrealistic assumptions will just take those problems with them — living abroad isn’t a clean slate.
Some things in life you can change. Some things you can’t. It’s not always worth getting mad or fighting against screwed up rules or banging your head against obstacles. Every person has to make their own decisions about what they can live with.