Musk, the world's richest person in the world, had an outsized role leading the Department of Government Efficiency as it canceled contracts and slashed the federal workforce.

But Musk was a creature of Silicon Valley, a scion of the “PayPal mafia” whose leadership and willingness to take big risks propelled him to unparalleled wealth and influence.

Musk called the legislation, which includes tax breaks, spending cuts and beefed-up border security, a “massive spending bill” that would increase the federal deficit and “undermines the work” of his ...