Is the act of thanking people too depreciated in modern times?

depends, if it was a service to you, like, a friend fixing a small thing on your car, then sure by all means pay them! but if it was like, i dont know, picking up something you dropped, why give them money? to be honest, these days i rarely ever hear a "thank you" so, when i do hear a "thank you" it makes me feel like they mean it.