The motivation is this interesting story... ' After a major military victory, the triumphant military generals were paraded through the streets to the roars of the masses. The ceremonial procession could span the course of a day with the military leader riding in a chariot drawn by four horses. There was not a more coveted honor. The general was idolized, viewed as divine by his troops and the public alike. But riding in the same chariot, standing just behind the worshipped general, was a slave. The slave’s sole responsibility for the entirety of the procession was to whisper in the general’s ear continuously, “Respice post te. Hominem te esse memento. Memento mori!”

“Look behind. Remember thou art mortal. Remember you must die!”

The slave served to remind the victor at the peak of glory, this god-like adoration would soon end, while the truth of his mortality remained. '

That story is given here in the section titled "Romans": https://dailystoic.com/history-of-memento-mori/

In this case, 'sic transit gloria' is another good one. sort of means, fame is fleeting. Also, the title of a great post-hardcore song.

Well-paid software developers from first world countries for some reason do like stoicism.

It worked quite well for both a Roman slave and the last, great Roman emperor, why not everyone else in between?

Epictetus? He gained his freedom before he began teaching iirc. And was influential and tremendously respected even before that. The contours of roman slavery are complex and I'm not fully informed on them but my understanding is that he would have spent much of his life closer to an emperor in status than to the chattel slavery that modern people are likely to imagine.

It seems that they engage in some degree of Epicureanism, as well.