a couple great quotes from Deng Xiaoping to explain:
Capitalism is a bane compared with socialism. Capitalism is a boon compared with medievalism, small production, and the evils of bureaucracy which spring from the dispersal of the small producers. Inasmuch as we are as yet unable to pass directly from small production to socialism, some capitalism is inevitable as the elemental product of small production and exchange; so that we must utilise capitalism (particularly by directing it into the channels of state capitalism) as the intermediary link between small production and socialism, as a means, a path, and a method of increasing the productive forces.
[…]
Get down to business, all of you! You will have capitalists beside you, including foreign capitalists, concessionaires and leaseholders. They will squeeze profits out of you amounting to hundreds per cent; they will enrich themselves, operating alongside of you. Let them. Meanwhile you will learn from them the business of running the economy, and only when you do that will you be able to build up a communist republic. Since we must necessarily learn quickly, any slackness in this respect is a serious crime. And we must undergo this training, this severe, stern and sometimes even cruel training, because we have no other way out.