Mr. Yuksel’s tale of living on borrowed money illustrates one of the ills plaguing the country’s economy and threatening a new financial debacle in an unstable region. It echoes the subprime mortgage calamity in the United States in 2008, in that the Turkish banks often seemed oblivious to the risk that their new customers might not pay them back.

The credit ratings agency Standard & Poor’s warned in a report last week that the boom in consumer credit had become a serious risk for Turkish lenders. Slowing economic growth, political turmoil and increasing reluctance by foreign investors to provide financing “are prompting a deterioration in the operating environment for Turkish banks,” S.&P. said.

Even as turmoil in Ukraine lately has overshadowed Turkey’s political and economic crisis, the problems here on the other side of the Black Sea have not diminished. On Thursday, Turkey’s dangerously weakened currency, the lira, lapsed to a three-week low as political opponents of Prime Minister Recep Tayyip Erdogan continued to raise allegations in the graft scandal clouding his government less than a month before local elections.

When foreign capital was flowing freely into Turkey and other emerging markets, the nation used it to splurge on consumer goods and real estate, rather than on new businesses that would support lasting growth. Now the bill is coming due. A big issue facing Turkey is what financial and political havoc this pile of consumer debt could create as a plunge in the value of the Turkish lira and a pullback by foreign investors forces the country to live within its means.

Much of Turkey’s rapid growth in the last decade came from consumer spending based on credit. Debt from credit cards rose 31 percent nationwide in 2012. In 2013 it rose an additional 22 percent. From practically nothing a decade ago, consumer debt in Turkey now equals 55 percent of household disposable income, according to Oxford Economics, a research organization in Britain. Until the Turkish government recently curtailed the practice, stores habitually offered to sell almost anything on installment, even a pair of jeans.