Musk rocket-boosted Trump's campaign - but will it all end with a bang?

"The future is gonna be fantastic," America's unlikely kingmaker posted on X, above a photograph of his Starship rocket blasting into space.

It was, after all, Elon Musk who strapped boosters to Donald Trump's campaign and helped propel him to a decisive victory.

The world's richest man bombarded his 200m+ followers on the platform he controls with pro-Trump content, some true, much false.

There's also evidence that, since Mr Musk endorsed the president-elect, X algorithms amplified pro-Trump content.

"I don't think this race would even be close if it wasn't for what Elon Musk was doing with X and showing people what is going on," said Mr Trump's eldest son - Donald Trump Jr - in a polling day podcast.

Throw in Mr Musk's tens of millions in campaign donations to Mr Trump, million-dollar giveaways to voters, appearances at his rallies and podcasts supporting him, and we have ourselves a winner.

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But what is in it for Elon Musk?

First is the role promised to him by Mr Trump as head of a new Department Of Government Efficiency.

This would give the billionaire the power to scythe through US federal bureaucracy that both he and Mr Trump say has long held America back.

Mr Musk certainly feels it holds him back. Environmental and safety regulations have, at times, delayed his break-neck rocket testing programme and the rollout of self-driving Tesla robo-taxis.

Mr Musk nicknamed the would-be new department DOGE - a reference to the Dogecoin cryptocurrency he often promotes - so quickly you wonder if the idea was his all along.

Removing regulatory barriers to his own business interests, or cutting contracts for his more cumbersome, government-dependent rivals like Boeing, would clearly appeal.

But Mr Musk is also ideological and wants to go much further - arguing there is $2tn (£1.55tn) in inefficiency to be slashed from the federal budget.

Many economists think this would be insane, gutting budgets for healthcare, education, science, environment and welfare, tanking the economy and fuelling unemployment.

But Mr Musk didn't become the world's richest man by doing things by half.

His purchase of Twitter for $44bn (£34bn) in 2022, was seen as a spectacularly bad business move. Does it look that way now?

Mr Musk also wants Mr Trump to deliver on his promise to promote the cryptocurrencies he backs ideologically and is invested in financially - even a plan to use a crypto price boom to pay down America's $35tn (£27tn) debt.

And Mr Musk's gamble in backing Mr Trump is already paying off. The value of his companies like Tesla has grown, if X and Space X were publicly traded, it's expected they'd have soared too.

The price of cryptocurrencies has also shot up at news of Mr Trump's victory, including meme coins like Dogecoin - long regarded as junk even by most crypto investors.

The Trump-Musk relationship takes America into new, very uncertain territory.

Big business has always sought influence in government - but never has the relationship been this close or exclusive.

And never between two men as madcap and morally removed from the mainstream.

But will the relationship endure?

Mr Musk might bring the White House Silicon Valley expertise and cash. He has promised to continue his America PAC donations to support Republicans. His control of social media is a formidable tool for the Trump administration.

However, Mr Trump's plans for aggressive tariffs could destroy Tesla's business with China.

Mr Musk has said "f*** oil," while the president-elect calls it "liquid gold".

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Then there's the two men themselves. Mr Trump has said he will accept only total loyalty in his new administration.

Can he - more his famously fragile ego - tolerate a man with greater wealth, a clearer mission, and possibly even a larger ego than himself?

Mr Musk is famous for not suffering those he sees as fools, and a willingness to blow things up in his dogged pursuit of success.

This could all end with a bang.