A few things here. Tramiel buying Amiga alone would not have guaranteed anything. Success at Commodore for the early computers was in the vertical integration and Amiga had none of that. Commodore had built that up during the calculator wars so even with a buyout its likely Amiga would have been quickly looking for another buyout by a larger company with more money and capabilities.
On the second persons point, Commodore under Tramiel may have been 'for the masses' and targeted to sell lower cost to the consumer, but that did not translate to Commodore not making profit on the 64. They didnt make much profit per unit, but that translated to more units sold and more profit, especially as competitors left the market meaning less competition against the 64. Technology is littered with 'boutique' brands bought out by the sucesfull mass marketers. Alienware's buyout by Dell for instance. Here was a maker of high end, high margin performance PCs bought by one of the low end consumer PC makers who does not make much per unit, but sells boatloads more units than Alienware ever could.
No one thing could have made Amiga succeed and I think it would not have done as well had it been purchased by an indavidual than having been purchased by Commodore with its chip manufacturing and, at least in the beginning, other profitable products to help fund R&D.
