Question: if you can invest in duopoly and the returns has been 7% + 1.6% dividend yield annually, would you do it ?

I have been reading old newsletters from 2007 to see which companies survived. And roughly 1/2 to 2/3s of them are no more ( well i am only in my 2nd issue), some of them shriveled like Liz Claiborne, now part of Kate Spade/coach, some became zombies post 2007/2008 GFC (eg. First Marblehead). So I was pleasantly surprised to see this company Quest Diagnostics DGX still around. You can read the original thesis in the link below. At first I was a bit dismayed that when it was recommended the price was $49 and after 20 years later the price is only $207. But when I thought about it, 8.6% (7% + 1.6% dividend yield) a year for twenty years isn’t a bad thing, especially at 2/3 the volatility of the S&P 500. Plus the company has only one other competitor, LH in a two horse race where the aging population is the tailwind. So would you invest in an almost 9% annualised returns duopolist for the next 20 years ?