Jim Rogers is bracing for the worst bear market of his life, de-dollarization, and higher interest rates. Here are the investing legend's 7 best quotes from a new interview.

• Jim Rogers is preparing for the most devastating bear market of his lifetime.
• The veteran investor sees higher interest rates and serious threats to the US dollar.
• Rogers is bullish on commodities and skeptical that governments will adopt bitcoin.

Jim Rogers is bracing for the biggest market downturn in eight decades.

The 80-year-old investor issued the grave warning during a recent RealVision interview. He also cautioned the US dollar's global dominance is under threat, and higher interest rates will be necessary to rein in soaring prices.

The cofounder of George Soros' Quantum Fund also slammed US lawmakers for the current debt-ceiling debacle, touted commodities as the best hedges against inflation, and dismissed the idea that governments will embrace bitcoin.

Here are Rogers' 7 best quotes, lightly edited for length and clarity:

1. "The next bear market will be the worst in my lifetime, because the debt has gone up by such staggering amounts in the past 14 years." (Rogers said the 2008 crash was caused by excessive amounts of debt, and borrowing has ballooned since then, suggesting a far worse downturn lies ahead.)

2. "We should always be concerned about Washington. They don't have a clue what they're doing. And they prove it day in and day out." (He was discussing the current political gridlock over raising the debt ceiling.)

3. "You should be extremely worried. If you're not, you don't know what's going on. Many countries are starting to look for alternatives to the US dollar, partly because of its horrendous debt problem. I'm looking every day, because I know that something bad is going to happen in the currency markets in the next two or three years." (Rogers was commenting on de-dollarization fears.)

4. "Interest rates are going to go higher worldwide. I don't know how high they have to go to kill inflation this time around. The world has never seen the debt and the spending and the money printing like in the last few years. So something is going to have to be very, very ruinous to solve this problem this time."

5. "There'll be trouble in all the markets — property markets, stock markets, bond markets, currency markets, everything. You have to learn about cash or selling short in order to survive what's coming."

6. "I don't think that the world is going to convert to bitcoin. It will be computer money, but it will be government computer money."

7. "The best place to be when you have inflation is real assets, and real assets are commodities. The cheapest asset that I know is still commodities." (Rogers said he owns some silver and gold currently.)