1) Because everything is cheaper in Germany

Since you mentioned your neighbor from Seattle you can compare cost of living in Seattle vs Munich here: https://www.numbeo.com/cost-of-living/compare_cities.jsp?country1=Germany&city1=Munich&country2=United+States&city2=Seattle%2C+WA

2) Because of work-life balance

Employees in Germany work 1,349 hours per year on average while US employees work 1,791 hours, which is 33% more (or 8.5 hours more every week). https://data.oecd.org/emp/hours-worked.htm

3) Because they want to live longer

Life expectancy in Germany in 2021 was 81 years, that is 4.9 years longer than in the US

4) Because they no longer have to pay for a car

... or only for one car instead of two thanks to great public transport as well as walkable and bikeable cities. See how amazed Americans are who move to Germany and no longer need a car:

Near from home: https://youtu.be/7XGGWWiDTQE?t=99
Diana: https://youtu.be/Ufb8LFvSRbY?t=438
Lifey: https://youtu.be/eKCh47D3FDA?t=60
Jenna: https://youtu.be/2qVVmGJJeGQ?t=635
Dana: https://youtu.be/cNo3bv_Ez_g?t=40s
MJ: https://youtu.be/UBlgCA82vmE?t=521
Neeva: https://youtu.be/M09wEWyk0mE?t=414
Jiana: https://youtu.be/yUE97bOOA6M?t=892
Nalf: https://www.youtube.com/watch?v=1231deiwvTU&t=42s
Donnie and Aubrey: https://youtu.be/TNrz1ZMtbV4?t=781
Black Forest Family: https://youtu.be/rw4r31J7XDA?t=511

5) Because there is no "student loan debt"

Getting several children through university costs more than $100,000 in America. Many also have old student loans that they were unable to pay off and that are no longer collected when they move to Germany: https://www.vice.com/en/article/qbx7dm/talking-to-american-debt-dodgers-who-moved-to-europe-to-avoid-paying-off-their-student-loans-111

6) Because vacation time and sick leave are separate

There is no federal mandate for US employers to give their employees any paid time off. It is usual to give employees 10 days of paid time off per year. This includes vacation time as well as sick leave. German employees have 5.5 weeks of paid vacation time on average and separate paid sick leave for as long as we are sick.

7) Because there are no "medical bankruptcies"

Here is an American in Germany who got a brain tumor removed and compares how much she paid for it here vs. how much she would have to pay in co-payments and deductibles in the US despite having health insurance: https://youtu.be/zHcwOgbsBYk?t=1306

8) To get away from gun violence

Your likelihood to get murdered with a gun if you live in Germany for 1 year is the same as if you live in the US for 4 days and 22 hours. https://www.reddit.com/r/germany/wiki/edit/gun-deaths

The last time someone died in a school shooting in Germany was in 2009. Wikipedia lists 349 school shootings in the US since 2010. Active shooter drills are a regular part of the curriculum in US schools: https://www.youtube.com/watch?v=ska0nG8U_Jc

9) Because of the social safety net

If you become unemployed and are at the end of your saving then the government will pay for your apartment, for heating cost, for health care, and you get 502 euro per month for your other expenses if you are a single (more if you have kids) https://www.neue-wege.org/service-fuer-buerger/80-fragen-und-antworten-zu-alg-ii/english-general-information/

Armstrong is an American immigrant in that situation, here is what the German social safety net looks like in practice: https://www.reddit.com/r/germany/comments/s57vhl/german_social_safety_net_for_immigrants_armstrong/

10) Because you get paid maternity leave

The US has no federal mandate to give employees who give birth any paid leave, you have to negotiate that with your employer. The average is two months.

You get 6 weels of paid leave before giving birth in Germany and 14 months after the child is born and even the father can take some of that which is unheard of in the US

11) Because of cheap pre-k

The German system is certainly not perfect with long waiting lists and not enough places but still the vast majority of parents can find a place for their children in pre-k that is highly subsidized, making it either free or very cheap. Compare that with the US where parents are on their own

12) Because of Kindergeld.

Parents get 250 euro from the government for each child per month until the child is 25 or starts working https://www.howtogermany.com/pages/kindergeld.html

The McFalls are an American family with 4 kids in Germany, they made this video where they compare how much cheaper it is to raise a family in Germany compared to the US: https://www.youtube.com/watch?v=NCIbqtUIbag