It's prudent to gain the whole world and lose your own soul. But don't forget that your soul sticks to you if you stick to it; but the world has a way of slipping through your fingers.
The most venerable, clearly understood, enlightened, and reliable constant in the world is not only that we want to be happy, but that we want only to be so. Our very nature requires it of us.
A lot of great fortunes in the world have been made by owning a single wonderful business. If you understand the business, you don't need to own very many of them.