The Chelsea legend was appointed by West Ham's former Icelandic chief Bjorgolfur Gudmundsson exactly two years ago.
Zola told The Sun: "Remember when I first took the job, the club was owned by one of the richest men in the world.
"We discussed what he wanted to achieve. He was a lovely man and he was football mad and totally in love with West Ham and with making them successful. We talked for hours... about how each year we would build the club.
"How we would add one or two more pieces every year and really turn West Ham into something special.
"It was an exciting idea and one I couldn't resist.
"But, unbelievably, within two weeks of starting the global recession had hit, the owner was broke and the whole scenario changed. My first feeling was of sorrow for him because he was a lovely person and back then I didn't realise the full impact of what had just happened.
"The truth is that the whole situation suddenly became the opposite - every year instead of adding one or two top players we had to sell one or two top players.
"And it was not about building a club, it became about saving a club."