Brake fluid should be changed every 3 years as it’s hydroscopic and absorbed water , and yes coolant should also be changed every couple of year and system flushed to remove sludge that forms , for someone earning 50k per year you seam a right tight wad 😂😂😂 none on theses things cost more than an hours earnings , you obviously don’t have any mechanical knowledge as anyone who has will tell you the same .