Most component upgrades don't make economic sense. There are some exceptions:

1. Something breaks or wears out.
2. You have a bicycle that you love and plan to keep forever. Sooner or later you're going to replace those parts anyway. Insted of waiting for things to break or wear out, make the bike exactly what you want now and start enjoying it now.
3. You have CBTD (compulsive bike tinkerers disorder).