Moderna tried mRNA for cancer and never made it to work, the technology is not mature and before covid vaccines they had no product on the market. Their first product was rolled out on the whole population with no proper risk-reward analysis, typical conflict of interest from connected people (from government and private sector) getting rich at the expense of the population (i.e., Mussolini's definition of fascism)

wingalt

science

Pfizer quickly sold mRNA vaccines but providing safety data not so much

The shots are known in the industry as 'gene therapies' . I suspect that Pfizer, Moderna etc knew that the public wouldn't take them unless they thought they were traditional style vaccines. 
But yeah the adverse events have been horrendous. I was looking at VAERs as early as January 2021 and the reports of adverse reactions were already piling up. I tried to warn people but very few would listen. 