Elon Musk had a good start to the week.

The world’s richest man added $36 billion to his net worth on Monday, as rental car company Hertz ordered 100,000 Teslas. The electric car maker’s stock surged on the news, enriching its founder and CEO.

Musk is now worth almost $289 billion, according to Bloomberg. With its recent uptick, Tesla is worth north of a trillion dollars, joining an exclusive list of companies including Facebook, Amazon, and Google-owner Alphabet.

Apple and Microsoft are each worth over two trillion dollars.

Musk’s $36 billion windfall is the biggest one-day gain in history. He is now worth more than Exxon and Nike and his fortune is larger than the combined assets of Bill Gates and Mark Zuckerberg.

But on Monday night, Musk took to Twitter to complain about a potential tax on billionaires currently being written by Sen. Ron Wyden, a Democrat.

“Eventually, they run out of other people’s money and then they come for you,” Musk said in a response to a tweet that suggested tax increases first imposed on the wealthiest Americans will eventually expand to include low income individuals.

In a second tweet, Musk continued “Who is best at capital allocation – government or entrepreneurs – is indeed what it comes down to. The tricksters will conflate capital allocation with consumption.”

Business Insider explains:

Musk is taking aim at a proposal chiefly authored by Sen. Ron Wyden, chair of the Senate Finance Committee, which may be unveiled as soon as Wednesday. The plan is meant to levy new taxes on tradable assets like stocks held by roughly 700 billionaires to fund an expansion of healthcare, childcare, and renew President Joe Biden’s beefed-up child tax credit.

Democrats say they are moving to tilt the economic scales of wealth away from the richest people and towards the middle class after years of growing inequality. Billionaires often pay lower tax rates compared to everyone else because they build up their wealth from the increasing value of their stock and shares. Those aren’t subject to capital gains taxes until they are sold.

Bloomberg adds:

The stock-based nature of Musk’s fortune has made it possible for him to gain billions of dollars in paper wealth and become the world’s richest person while having few liquid assets. He accepts no salary from Tesla and part of his stake is pledged as collateral for personal loans, according to company filings. He told a federal jury in 2019 that despite his multibillionaire status, he didn’t have much cash. Last year he announced on Twitter he planned to sell his homes and “almost all” his physical possessions.