Buddy if you “we” could do that “we” never would have been employees in the first place.
Workers already are the ones who design and build machines, but our capacities are constrained by business owners, who control the resources of society, including the enterprise that conducts research and manufacturing, and who direct the labor of workers for using the resources they control.
If you think automation is not profitable then you vastly underestimate the costs of running a business and hiring human employees.
You are attacking a straw man.
Some automation is profitable, at any particular time, but some automation may improve the experience of workers without being profitable.
Various relevant factors include the availability of technologies previously developed through public investment, the degree by which private enterprise is competitive versus monopolized, the structure of the labor pool especially in its degree of stratification, and the relative profitability of other investment opportunities, such as those more overtly framed around speculation, predation, extraction, or exploitation.