Son, one of the world's richest individuals now, saw almost his entire wealth being wiped off in the wake of the 'dot com' burst in 2000 as Softbank's market capitalisation plunged from USD 200 billion to just USD 2 billion.
"I was richer than Bill Gates for 3 days. So in that year, my net worth was growing at USD 10 million a day and I started asking myself what is money.
Admitting that he even felt sad at that time, Son said, "Its actually sad to be rich".
Son said he was thinking of donating his wealth till the 'dot com' burst happened.
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"I got the answer to my question. Next year, I lost 99 per cent of that. So I didn't need an answer to my question... In 2000, I actually became happy. After losing 99 per cent, I said now I have to work. Now I feel the joy of work, now I feel the value of money, again," he said.
"So I am excited again that after having a tough time, I understand the value again and I am still betting for the future," Son said at the HT Leadership Summit here.
SoftBank, which has invested in multiple startups in India, including Ola, Snapdeal and Oyo, has also designed a robot called 'Pepper'.
Asked about how he would want to be remembered, Son said as a "crazy guy who bet on the future".
The net worth of Son, who is the second richest person in Japan, is estimated to be more than USD 17 billion.