I like cycle touring, and im gonna embark on a trip across australia soon. A few people have told me i should do it for charity but like why?

Me riding my bike has nothing to do with any charity, i enjoy it its a holiday of sorts. What makes people donate to charity because i rode a bike as opposed to just donating to charity themselves?

If anything it seems self defeatist. If im gonna spend $5k+ on a months long bike ride Solitaired and then say im doing it for charity, if i raise anything less than 5k (which is quite likely) it would have literally been better for the charity if i didnt go on the trip and just gave them 5k.