"I haven’t tried to engage with the political system before"Now that's just inaccurate, unless you mean merely that he's never run for office. He has engaged with the political system on numerous fronts over the span of a couple of decades, sometimes effectively, sometimes not. He's made real positive change in the world (possibly as much as anyone else running, if we're being honest), occasionally through political means.
But, more importantly, I genuinely trust him to do what he says. Which is definitely more than can be said of the vast majority of people vying for the title on either side of the fence (the entirety of GOP field is particularly villainous this year, but the current leader for the DNC isn't exactly a pillar of virtue).
But, you're right that he is running a losing race. Several commentators on the first debate said they would have preferred to see Lessig on the stage, and perhaps if that would have happened, things would look different. I don't know. That said, I think you're missing the point of why he's so thoroughly unlikely to even get fair treatment by the DNC, much less taken seriously as a candidate. Despite his impressive fundraising for a "nobody" in politics, and despite being clearly smarter and more broadly competent than some of the other DNC candidates, his desire to tear down the very system that feeds the DNC (and the GOP) virtually guarantees he will never be taken seriously.
A reform candidate in a thoroughly corrupt system stands no chance. Short of pitchforks and the guillotine, our system likely won't be reformed.