Is there evidence sanctions strengthen a regime? With Russia at war right now, sanctions do indeed seem to be helping Ukraine with Russia having a budget crisis.
Sanction strengthen the political grip of a regime on society, which can use them as a justification for its repression. They also hollow-out the middle class, which prevents a democratic societal change, which requires it.
In the case of a war, it is of course useful, but it won't solve the long-term issue of the nature of the Russian regime, which has gotten only more entrenched since 2014.
“ sanctions strengthen authoritarian rule if the regime manages to incorporate their existence into its legitimation strategy.”
https://www.cambridge.org/core/journals/european-journal-of-...