Company wants me to give a rough estimate of developing a new feature in a distributed legacy monolit. They told me they would inform me the next day and want the estimate on the same day for a project that will probably take 2 devs 3-4 months. I ask for more time and info, give the estimate and they say it "feels too much". I mean ok. Then why am I even estimating? If in the first place the client has only X money than do the project for X and it doesn't really matter how much work it is, does it?

tell me..?
if i am NOT doin any proj and i am just learning and solving problems on competitive websites like codechef , hackerank etc.
is it a bad thing ?
or should i just continue learning this way?
P.S I AM TRYING TO BE A SELF TAUGHT DEV !