The old advice to keep politics and elbows off the dinner table may need to be updated to include bitcoin this year.

Last year at this time, the cryptocurrency was just entering its hot streak, soaring in price because retail investors were buying. But it's likely to be a sore subject for people who bragged during last year's holiday feast about their new investment idea.

Your relatives who took the smug brother-in-law's advice and bought $1,000 worth of bitcoin during the week of Thanksgiving 2017, have lost about $450 of that investment. Those who waited to buy until the week after Thanksgiving 2017 have lost $550. And those who resisted temptation to buy until the week before Christmas last year have lost around $763 of that $1,000 investment.

Bitcoin first topped $10,000 in the last days of November 2017, and by mid-December was worth almost $20,000, according to data from CoinMarketCap.com. Contrast that to this Thanksgiving: Bitcoin's price has sunk back below $4,300 for the first time in 13 months.

Kyle Asman, partner and co-founder of crypto advisory firm BX3 Capital, began using cryptocurrency in 2013 for online gambling. He was shocked when bitcoin came up at his own dinner table.

"Before that it was more of a closet thing," Asman said, though he did notice the price started spiking last year around the holiday. "I remember that was the only time I had talked about it at my Thanksgiving table — some described it as digital gold, others as a new form of money."

In the weeks after Thanksgiving, the price moves became even more exaggerated. Asman recalled being at a holiday party, going into the restroom when bitcoin was $9,000 and returning minutes later to have a friend tell him it was trading at $11,000.

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