单项选择题

Computer programmer David Jones earns ￡ 35,000 a year designing new computer games, yet he cannot find a bank prepared to let him have a cheque card(支票卡). Instead, he has been told to wait another two years, until he is 18.
The 16-year-old works for a small firm in Liverpool, where the problem of most young people of his age is finding a job. David’s firm releases two new games for the home computer market each month.
But David’s biggest headache is what to do with his money. Despite his salary, earned by inventing new programs, with bonus payments and profit-sharing, he cannot drive a car, buy a house, or obtain credit cards.
He lives with his parents in Liverpool. His company has to pay ￡ 150 a month in taxi fares to get him the five miles to work and back every day because David cannot drive.
David got his job with the Liverpool-based company four mouths ago, a year after leaving school and working for a time in a computer shop. "I got the job because the people who run the firm new I had already written some programs," he said.
"I suppose ￡ 35,000 sounds a lot but I hope it will come to more than that this year." He spends some of his money on records and clothes, and gives his mother ￡ 20 a week. But most of his spare time is spent working.
"Unfortunately, computing was not part of our studies at school," he said. "But I had been studying it in books and magazines for four years in my spare time. I knew what I wanted to do and never considered staying on at school. Most people in this business are fairly young, anyway."
David added: "I would like to earn a million and I suppose early retirement is a possibility. You never know when the market might disappear.\
David thinks he might retire early because ______.