The Tesla chief tweeted support for virtual money in what he called the 'true battle' with traditional fiat currencies.
But it wasn't enough to stop bitcoin tumbling.
On Sunday (May 23) it sank as much as 17%, hitting a low just about $31,000.
The trigger was fresh worries over Beijing's moves to curb speculation.
China's cabinet has announced plans to crack down on so-called miners - the firms that produce bitcoin through energy-intensive number crunching by computers.
Some of the country's top miners have suspended operations as a result.
By Monday (May 24), bitcoin had regained much of the lost ground, climbing back above $36,000.
But that still left it at little more than half the peak seen last month.
Prices are now back around where they were in February, when Tesla ignited a rally by announcing it had bought $1.5 billion of bitcoin.