Well no, you're right. He's never managed to win any election. Or even a leadership bid within his own party. And unlike Trump he also appears to has no interest in making the country he rules richer or more powerful.*
I am obviously not comparing the policies, I am comparing the approach. Populism does not lean left or right, it targets the angry, ignorant masses. I suggest reading up on Rome circa 2nd Century BC to the fall of the Republic and the rise of Octavian/Augustus. Populists in all shapes and forms, with one thing in common; rousing the rabble. This is what happens when you have a large, uneducated population. And is the most persuasive reason for ensuring you have a large, uneducated population.
To be clear, I am also not remotely suggesting this one is in the league of the Gracchi, Caesar, Augustus, or even Clodius! He's a very, very pale shadow working from the same well-worn playbook. But as he's so far not even managed to even come up with anything new, I doubt he'll last long. Or maybe that's wishful thinking; I am genuinely shocked at how many presumably grown women have had their heads turned by a man whimpering on stage whilst repeating the exact same things most of his predecessors have said, with even less understanding of basic economics and geopolitical forces.
And yes, I'll happily admit to be rattled; 'he's a hateful, divisive, bitter little charlatan. He's more populist than Trump, and has so far demonstrated even fewer morals.' And he's suddenly, bizarrely in charge of the country, implementing policies nobody voted for which will cause enormous and permanent harm to all of us. If you're not rattled, it's because you don't understand the enormity of what's happening.
*As no doubt your next retort will be that I must be a Trump voter, I will pre-empt it by saying I am most certainly not - Trump is absolute scum, I despise him and his entire cabinet, and think they should all be in gaol. I am however very interested in why people would ever vote for a creature like Trump, and I see the exact same answer in why people would swoon over Burnham.