Source: https://www.solipsys.co.uk/new/SellYourselfSellYourWork.html?yc25hn

for you to benefit fully from your work, you have to make it known

and from Richard Hamming:

it is not sufficient to do a job, you have to sell it

The author doesn't mean sell in a monetary value per se (although money is never bad, as money allows you freedom to do things), but selling as a concept to effectively communicate your work so that others notice it, understand its value, and can benefit from or build upon it. Ultimately, everyone wants their work to have impact, gain some recognition, and avoid being wasted - otherwise, what is the point (aside from personal development[1])?

I am horrible at this and I don't want to calculate the time and opportunity lost. It will be too depressing. But the time to change is now.

Footnotes

1. That is the rationale for why I stay silent in some respects - I do this for enjoyment. The problem is it doesn't lead to new opportunities.