Sinclair remains the only New Zealander to ever score a double century on debut, smashing 214 against the West Indies in Wellington in 1999.
The lanky right-hander managed another double ton against Pakistan the following season but never cemented a spot in the national team, appearing only sporadically until his last Test in 2010.
At 37, Sinclair, who has a wife and two young children, said he could no longer rely on income from playing for the Central District Stags during the summer, then looking for casual work in the off-season.
Until then, Sinclair said he would have to sign on for the dole -- a stark reminder that not all promising cricket stars go on to fame and fortune, particularly in a small market such as New Zealand.
"It has been very hard to look for some sort of meaningful employment... I had to make a conscious decision to give up the game to make myself more marketable," he told Fairfax Media.
