Because they couldn't "meter" the power his tech generated.

Yes, ultimately, money and power. Tesla offered a world where free energy existed along with many other technological advancements....a truly remarkable man who i dont think gets the credit or respect he deserves.

This was at a time of industrial revolution where you had massive wealth and power being held by titans of industry. Titans whose fortunes depended on Tesla going bye bye. If you control the energy, you control the power literally and figuratively speaking. Tesla and what he was capable of rocked the boat wayyyyyy too much. He had to go and so, he went. Energy dependence was crucial to maintaining and amassing power to then exert that power and exploit it in every way possible to further your own agendas and wealth. Rockefeller and his boys had too much skin in that game to let the cash cow dry up.

This same thing happened all over various industries. It's the same principle reason why industrial hemp was outlawed. Cultivation and manufacture of hemp for paper, wood, and the other 840 products you can make with it would have absolutely crushed the paper and timber industries plus others via association. Only in this case instead of murdering a pioneer they successfully lobbied congress to pass legislation requiring a marijuana tax stamp. Which subsequently they would not issue said tax stamp effectively destroying the largest threat to the US paper and timber industries.

Seems like more often than not power and wealth have always been the motivating factors in suppressing human progression and advancement.

More money in gas. In fact, Tesla had discovered FREE energy for the world.

Sheer nonsense and an urban myth. He was never silenced. Who could do it? He was endlessly promoting himself and his ideas. But as he grew older, the proportion of visionary speculation outstripped his practical accomplishment, and he was often talking about grand possibilities that no one understood how to accomplish, promising revelations that never materialized. Wireless power was never demonstrated. If you speak visions, but no ear can decipher your language---are you "silenced"? His final years were self-isolated and in penury, kept afloat by a stipend from his old partner, George Westinghouse. World War II was in full swing. There were other concerns to listen to.

The FBI was aware that Tesla's only heirs were in Serbia and doubtless motivated their action of sequestering Tesla's papers for assessment as to whether they might represent a threat in foreign hands. They enlisted Dr. John G. Trump to assess Tesla's material, which he found to be harmless and unremarkable. In 1952, on pressure from Tesla's nephew, Tesla's estate (in 80 trunks) was sent to Serbia in 1957. The idea that the FBI is holding his files of miraculous inventions is unsupported. There is no secret Tesla technology.