As Morikawa pointed out, having a girlfriend (he specifically mentioned "girlfriend") is not about being handsome or rich, it's a time and energy investment.
"If begins thinking, 'I can't get a girlfriend, but that's not big deal,' that is a serious illness," said Morikawa. One of the symptoms, he professor continued, was to erase the gap between one's dreams and one's reality.
"You really want a someone to love. But in reality, you cannot," continued the professor. "However, if you brush that off and use the excuse that you don't want a girlfriend, then you're trying to ease your serious heartbreak."
This does not pertain only to fringe dudes (see above) who ride the train with hug pillows, but regular, totally normal folks, too.
While I do agree that covering up one's desire for companionship does lead to heavy hearts, not everyone is able to easily find a member of the opposite sex that's right for them. Saying you don't want a girlfriend (or boyfriend) could be the only way to cope.
「『彼女がいなくてもいい』は一種の病気」と恋愛学の権威が指摘 [Yahoo! Japan]