Even for the world’s richest person, $US43 billion ($57.95 billion) is a steep price.

Elon Musk’s proposed all-cash offer to buy Twitter Inc. represents about one-sixth of his $US250.6 billion ($337.7 billion) fortune.

Musk has offered to buy Twitter to make the company private and “unlock” its potential as a platform for “free speech”.

Social media expert Ming Johanson told Gary Adshead, hosting 6PR Mornings in place of Liam Bartlett, that Musk is a man who thinks 20 steps ahead of everyone else and his motives for buying Twitter were unknown.

“There’s certainly lots of reasons why he would want control over the platform,” she said.

“You really have to think about what it is that is motivating him.”

Tension between Musk and Mark Zuckerberg, Facebook owner, has been brewing for some time.

Tap PLAY below to hear more from Ming Johanson on Elon Musk’s motives