Oil companies have far worse profit margins than say Apple or Microsoft. They have good years and bad years but Exon regularly trades below 10 P/E where tech companies often trade above 20 because tech companies are far more capable of long term growth and far at the whim of classic inelastic supply demand curves. (In other words if oil when back to 30dollars a barrel people would buy more oil, but they would not do so quickly.)

As to iPad's many people buy tablets and never load a single app on them. Unlike consoles where the device is subsidized by the software sold apple treats it's app store as revenue neutral. They have income but they poor it back into iOS development, because long term the OS with the best software wins and they can still make fat margins on the devices themselves.