No activity in the U.S. is more heavily subsidized than home ownership, which gets tax breaks worth at least $70 billion a year. But as politicians search for ways to reduce the deficit, a new poll commissioned by the Federal National Mortgage Assn. demonstrates the danger of tampering with these tax goodies. The survey of 1,521 households, conducted by pollsters Peter D. Hart and Robert M. Teeter, found that 71% of Americans would give up two weeks of vacation a year to be able to own a house. Nearly 60% would give up a decade of early retirement as the price of home ownership, and 57% think taking a second job was a worthwhile sacrifice to own their residence. The main reasons folks want to own homes: freedom from landlords, a sense of belonging to the community, and investment potential. More than half cited tax breaks as a "very convincing reason" to own.