Teeth whitening

As I get older, it seems that tooth discoloration worsens.

They say it gets worse if you drink coffee, but since I always drink coffee and don't drink water... I hear you should brush your teeth after drinking coffee, but since I mainly drink coffee when I go out, I can't do that. They also say to rinse with water, but I don't notice much effect, maybe because of discoloration. Do I really need to go to the dentist for whitening treatment? It seems effective, but the cost is burdensome. ㅜㅜ

Has anyone seen effective results with the methods available on the market or with products currently being sold?