The stock markets around the world have been propped up by central banks since the financial crisis.
The FED stepped in with a few trillion in QE to save wall street. The ECB implemented their own QE. BoJ also in japan. And even china has stepped in to prop up it's stock market although their stock market is much younger, smaller and less systematically important.
And so the world goes round and round. Historically, printing money and artificially propping up assets doesn't end well, but if everyone is doing it, maybe it'll work out?