IMHO, there are likely multiple reasons including:

1. Money per injection,

2. Punitive, hate/disdain for the sheep - they want you dead, maimed or permanently ill,

3. Money from treatments, therapeutics and short-term, long-term and hospice care from dying, maimed and permanently ill customers (patients), their insurance companies and the governments,

4. Power - a reduced and/or weakened populace is easier to control,

5. Satanic/evil rituals,

6. Blackmail of MANY policymakers, decisionmakers, researchers, medical/political/administrative officials, media personalities, operatives and "regular people" who've chosen to make and (seemingly) follow mandates, rules and laws that sacrifice the public rather than be exposed for their wrongs/illegal/immoral activities or have themselves or their families killed,

7. Actual scientific curiosity to see what happens to the test subjects after the jabs,

8. "Mad scientist" curiosity to observe what happens to the test subjects after the jabs,

9. Health/welfare - some may actually believe the jabs are "safe and effective" and

10. Other