Slate tries to explain:

He’s putting money in their pockets. Mubarak’s supporters out on the street may be on the government payroll, and his natural power base comprises the wealthy Egyptian elites. The president’s relatively open, free-market policies have broadened trade (PDF) with the West and Israel, and made thousands of local businessmen extremely wealthy. Add that to his record of extracting foreign aid from the United States and distributing it to domestic businesses, and there’s an entire class of Egyptian entrepreneurs who have benefited greatly from his leadership. Government bigwigs, especially those inside the Interior Ministry, are also staunch Mubarak supporters. Then there appears to be a group of ordinary Egyptians who support Mubarak because they think his leadership can at least stave off Yemen-style chaos or Iran-style theocracy. But those people are few. Overall, Mubarak’s support among the working class is very weak.
There’s no way of knowing precisely which, or how many, people support President Mubarak, because he has never allowed pollsters to ask people for their opinion of him. (He didn’t permit any polling at all until the last decade or so.) But there’s reason to believe that his message during the 2005 elections—an odd combination of progressive slogans like “New Thinking” and scare tactics—didn’t convince many people. Only 25 percent of eligible voters showed up at the polls, and many observers think that number is inflated.
It’s pretty clear that the people riding into Cairo on camels and armed with whips don’t represent a spontaneous pro-Mubarak movement. Journalists have noted that many of them arrived simultaneously, they carry identical flags, and they have an uncanny ability to act in unison. Egypt-watchers assume these activists have been hired to interfere with the protests.
President Mubarak’s National Democratic Party has around 2.5 million members, which represents 3 percent of the population. But even that puny total overstates the party’s popularity, since few Egyptians join the NDP for ideological reasons. (The party didn’t develop its current free-market platform until the last few years, anyway.) Patronage is the real draw