Brokers make money by buying and selling stocks on your behalf. Yes, they try to get you to invest more and more with them, as much as you can. The only way for brokers to make money is to sell some of the stocks you own, and buy different stocks. If the client makes money, too, that's wonderful. But brokerage houses, big and small, exist primarily to make money for themselves, not for clients.
Brokers like to present themselves as investment counselors.
But first and foremost, they are salesmen. P. F. Collier and Son. Idols of the mind. Accessible account of the history of the measurement of risk in contrast to uncertainty and in particular investment risk. Silent on the important paradox-resolving Allais Paradox in discussion of the St. Petersburg Paradox, and silent on the more appropriate Stable Law distribution in discussion of normal or Gaussian probability distributions of changes in stock market prices.