If it is illegal to stalk someone for personal reasons, shouldn't it be illegal...

[Michael S]

...to stalk someone for money? Stalking is illegal because it is harrassing and invading someone's privacy. Why should photographers be allowed to harass and invade celebrities' privacy just because they can sell their pictures? Isn't everyone who buys their pictures a stalker by proxy, paying the paparazzi to stalk celebrities for them? Wikipedia says: Paparazzi is a term for photographers who take candid photographs of celebrities, usually by relentlessly shadowing them in their public and private activities. Celebrities claiming to have been hounded by such photographers often use "paparazzi" and even "stalkarazzi" as a pejorative term.

[sadhu1601]

Stalking to take pictures of celebrities is legal as long as it's on public places or it's on a private thirdparty property and its owner doesn't mind.

Celebrities get their fame and financial success due to public spending money on their movies or music concerts. Most celebrities are expected to "give back" by sitting for interviews, posing for pictures, etc. For this reason few celebrities can win anything in court for being stalked, unless it's for something defamatory.