Spencer Pratt — the 2000s reality TV star turned 2010s online influencer turned 2020s populist firebrand — is now a formidable candidate in the L.A. mayoral race, gauged by fundraising totals, poll numbers and incoming criticism from chief rivals. This ascent is a shock for the city’s liberal establishment, which considers him an unqualified clown. It shouldn’t be. His reactionary run, a revivalist pitch to make the city “once again ‘camera-ready’ for all its citizens” by cracking down on crime and corruption, has gained traction with his rollout of a slick and mischievous digital strategy. It culminated in a recent campaign ad rollout riffing on Kendrick Lamar’s “Not Like Us” to knock his competitors, incumbent Mayor Karen Bass and progressive L.A. City Councilmember Nithya Raman . The button on the spot was a callback to his own Act I inciting incident — how his house burnt down in last year’s Pacific Palisades wildfire as a result, he insists, of government incompetence.…