It's possible that he is in a hurry and the elevator is not working. So he has no choice but to climb the stairs all the way up to the 19th floor. This could also mean that he has some urgent business to attend to on that floor, like an important meeting or to check on someone who is in distress.
He could be doing it for a bet. Perhaps he wagered with his friends that he could climb that many stories.
Maybe he is trying to get a better view of Paris from a higher place.
It depends on his fitness level. If he is very fit, it might take him around 10 - 15 minutes.
It could be a dare or a part of some extreme fitness challenge he set for himself. Some people like to push their physical limits in unique ways, and climbing 15 stories is no easy feat. It might be his way of proving his strength and endurance to himself or others.
It could be that the elevators are out of order and he's in a hurry to get out of the building, so he chooses to climb down 15 stories. There might be an important meeting or appointment he doesn't want to be late for. Also, perhaps he just wants some adventure or a physical challenge, although climbing down 15 stories is quite a risky adventure. He might be a thrill - seeker who likes to do extreme things.
It could be that he is in an emergency situation. For example, there was a fire in the building and the stairs were blocked, so he had no choice but to climb the outside of the building. And he might have some basic climbing knowledge and enough courage to attempt this dangerous climb of 15 stories.
If he was climbing for a legitimate reason, like a rescue operation or if he had prior permission from the building owner, then it could be legal. But just randomly climbing 15 stories of a building in Philadelphia without any authorization is likely against the law.
It's hard to say for sure. Maybe he was driven by revenge or some deep-seated psychological issue.
An adventurous person might do it. They love to take risks and seek challenges, and climbing 15 stories is definitely a huge challenge.
Perhaps he needs the jewels to save someone's life. Maybe a loved one is in danger and the only way to get the ransom or the cure is through the jewels. So, he resorts to stealing them, thinking he can make up for it later.
Her motivation could be kindness. Just seeing someone in need, she felt compelled to help.