Define “thriving,” even the most famously abusive Socialist economies like the USSR managed to double life expectancy, and achieve other good metrics like free Healthcare and education, which even modern Capitalist economies struggle with.
“Capitalism” did not make everyone’s lives better. Development did. That’s why the USSR, in spite of its top-down, brutal structure, managed to double life expectancy.
Simple “blind brand loyalty” and monopolization are not the only hallmarks of “Late-Stage Capitalism.” Other hallmarks include rampant consumerism, bullshit jobs, stagnating wages with respect to productivity, further alienation from labor, increased Imperialism, and more.
Blind brand loyalty isn’t the issue here, and you cannot “fix” Capitalist exploitation within Capitalism, only make it more bearable.
All in all, lots of assumptions with no ground to stand on. As a leftist, I think it’s safe to say that democracy is generally a good thing, as is decentralization, so a better system than top-down Capitalism would be an economy with democratic participation from the bottom-up. Communism can achieve this.