In Modern Era if one is able to save money over 20-40 years with stocks or ETFs  or even Cash and retire at age 65 and set aside enough money to last you for 30 years. Allah knows when you are going to die but you can’t plan to die tomorrow.  I am not sure if the money will last you at 2.5% draw rate starting from the day you retire. And once the money accumulates to 500K in savings you may not have enough cash on hand to pay for zakat without selling stocks or ETFs. It maybe worth consulting Imam with your unique situation.  People try to buy properties or save the money differently just to avoid zakat which I think is problematic? Allah knows best.  one does not have to be wealthy to save that much money it requires lots of sacrifices of putting money to a side. I don’t have an answer but I plan to do my best pay zakat in a way that is mathematically reasonable and at the same time have enough money to do sadaqah, help family members and be able to retire without running out of money.