In this specific case it was a reserve of almost 10 years ago, when bitcoin was worth pennies, at the time he was very young and he didn't imagine that bitcoin was worth much in the future making the withdrawal
for original bitcoin wallet software without worrying about storage and without taking care of the private key. Bitcoins were stored on the computer's hard drive, that's when it happened formatting and bitcoins are lost forever. It was very common in the early days of bitcoin for many people to explore bitcoin just for fun, as bitcoin was not thought to have such significant value as it does today.