If you think INFN has significantly better prospects than TSLA going forward, then selling TSLA and buying INFN is absolutely the right thing to do.
I can give you much better or rather interesting language for this.
We had an extremely popular and influential advisor by the name Bill Mann who founded PayDirt, Global Gains and Fool Funds. He was also the lead advisor for HG for a few years and those days were eclectic. We used to have a 10-20% pop in seconds after a new rec was released. Then the whole show collapsed and while it was collapsing, he left all TMF newsletters to found the Fund.
He used to say: “Every day, every one of my stocks is at sale, for the right price”. The logic is mesmerizing. Isn’t it? This is how he justified many of his sells at market peak in 2006 and he turned out to be right. But that was also a period where every sell would make the investor appear to be a genius. His mojo soon left him as his high convictions picks collapses one after the other and then later he sold firms like CMG and GWR and countless others on this logic only to see them gallop away to multibaggers. He even bought back CMG after missing more than a double in FoolX portfolio with an editorial admitting his mistake but the sells have continued. After 5 years, all FoolFunds perform sub par to SPY and only marginally better than the arbitrarily chosen indices. I occasionally send him jibes by posting on his Question authority. My latest was: "how is it your portfolios are out of cash at market peal when you justified holding high cash levels during 2009-10? " Of course, I never get responded back. But I digress. The problem is with false precision. There is no way of knowing precisely whether or not a company is overvalued since DCF analysis assumes a certain path in the future which is usually highly volatile and this creates false precision. He has been an abject failure so far. Today the Fool Funds perform exactly as TMF used to critique mutual funds a decade ago. The team has more of the folks that think like Bill Mann today - DCF based false precision. Now this can be done right. And some folks have shown it indeed. We have Jim Mueller’s rising star portfolio that is climbing in strength all the time, we have IV whose picks actually thrash the market with this methodology and then we have MFO where we see 90% accuracy based on careful analysis. But all these folks are exceptional individuals with amazing skill and insight. I will give TMF credit for tinkering constantly and be filling to fail to get these gems out there over time.
So yes, you are technically right that jumping to a better opportunity should lead to good results. The problem occurs in determining if the opportunity is actually a better one. The uncertainty of the future leads to rather unpredictable results. That is why I really want to track Saul going forward with reasonably precise spreadsheet so that we can all learn this remarkably useful skill. If anyone is actually that good or becomes that good who can do the flipping with > 60% precision, that person will become one of the leading investors in the world (rate of return wise) in 20 years. And probably quite rich. With results like Saul and for that long, I can only imagine him to be living in a mansion with butlers. I am sure he is modest enough to not let such vanity consume him.
Anurag