Just think for a moment: why would a for-profit company go through the cost of filing a patent application if they didn't expect to obtain a return? Seriously, give it a moment. Those IP lawyers aren't cheap. It works even if only a small percentage of patents provide the lion's share of the revenue.
Look at any settlements between multinationals and see the role that patents play at the negotiation table, for instance.
Also, re. Qualcomm, it actually makes the majority of its revenue from IP licensing, not its sale of chips.