Polling and analysis show Vivek Ramaswamy had a short-lived bump around the time of the first GOP debate, but he did not continue to build increasing momentum into fall 2023, nor did he meaningfully peel off Trump loyalists.

By debate day (Aug. 23, 2023) his main surge had already occurred: FiveThirtyEight’s national GOP primary average had him at about 10% support, up from roughly 4% in early July, making him a distant third behind Trump, who was near 50%.【(fivethirtyeight.com)】 Immediately after the debate, multiple national polls showed him mostly in the mid‑single to low‑double digits (roughly 6–12%), again solidly in third place and far behind Trump’s ~50–60% share.【(en.wikipedia.org)】 That is a modest bump, but it reflects a rise that had largely already happened by late August rather than new, sustained post‑debate momentum.

Through September, his national support plateaued in that same range (around 5–10% in most polls), and by October–November he was drifting downward: many polls had him in the low single digits to mid‑single digits, often behind both DeSantis and Haley, while Trump’s lead remained overwhelming at about 50–60%.【(en.wikipedia.org)】 This pattern is inconsistent with “really building momentum going into the fall”; it is better described as a brief late‑summer spike followed by stagnation and decline.

On Trump loyalists specifically, a FiveThirtyEight analysis found that Ramaswamy’s second‑choice numbers among Trump voters did rise sharply (from 8% to 26% between early June and late August), but it also emphasized that a disproportionate share of the most conservative voters remained firmly committed to Trump and “haven’t necessarily been available” to Ramaswamy or others. The piece concluded he was still a long‑shot, with Trump commanding about half of the primary electorate and most of his supporters saying their minds were made up.【(fivethirtyeight.com)】 Morning Consult’s post‑debate tracking similarly showed Trump’s perceived electability increasing to 62%, while the share of GOP primary voters naming Ramaswamy as most electable actually fell from 10% to 6%, and his unfavorables nearly doubled as more Republicans learned about him.【(pro.morningconsult.com)】 These data do not support the idea that he built substantial, durable momentum among Trump loyalists specifically.

Overall, Ramaswamy enjoyed a breakout moment and some short‑term gains in late summer 2023, but he did not keep building significant momentum “over the next few weeks and into the fall,” nor did he become a major magnet for Trump’s base. That makes Chamath’s forward‑looking prediction, as normalized here, best classified as wrong.