$C3.ai (AI.US)$ is this still a good stock? or move the investment to Nvidia and others on the list below?

$NANO Nuclear Energy (NNE.US)$ what happened? why is this going down? or will it go up still?

$NVIDIA (NVDA.US)$ is it too late to buy?

$SoFi Technologies (SOFI.US)$ Please let me know when it’s time to sell. New at this.