Thousands of other digital currencies had fallen by 90-99% from their peaks as of October 2018.

Judge as of 15 Oct 2018. True: data show that thousands of crypto tokens or coins (at least about 1,000–2,000) had fallen 90–99% (or more, including dead coins) from their peaks. Mostly true: the count was in the high hundreds to low thousands, or many had fallen by 80–90%, with the gist intact. Mixed: hundreds rather than thousands had such declines, or declines were typically 70–90%. Mostly false: only a small number fell 90–99% and most falls were much smaller, so the claim overstates a narrower fact. False: few cryptocurrencies had fallen that much.

Set before the research began.

1. E1 The Rise and Fall of Cryptocurrencies Feder, Gandal, Hamrick, Moore, Vasek (Tel Aviv University / University of Tulsa / University of New Mexico working paper) · 4 June 2018

   “More than 75% of the coins declined in value. 25% of the coins lost more than 60% of their value. More than 95% of the valuations fell.”

2. E2 Can altcoins survive $650bn of losses? MoneyWeek · 23 September 2018

   “Between them, they have lost almost 80% of their value. Within that, there have been some even more spectacular falls. Neo at one point was down by 92%. Cardano was down by 95%. XRP fell by 93% and Bitcoin Cash by 90%.”

3. E3 As The Bitcoin Price Plummets, Its Dominance Is On The Rise Forbes · 27 November 2018

   “Bitcoin's epic bull run last year, that saw its price soar from under $1,000 at the beginning of 2017 to almost $20,000 towards the end of the year, dragged hundreds of so-called alt coins along with it—with many of them now collapsing entirely.”

4. E4 83% of cryptocurrencies that peaked in 2018 are still down by 90% Cointelegraph · 21 January 2021

   “The data set included 410 assets that posted record prices during 2017 or later, with 2018’s 157 star coins performing the worst with an average of -90.71% since the previous ATH.”

5. E5 The Rise and Fall of Cryptocurrencies Tel Aviv University, Berglas School of Economics (working paper by Feder, Gandal, Hamrick, Moore, Vasek) · 4 June 2018

   “Overall, we find that 44% of publicly-traded coins are abandoned, at least temporarily. 71% of abandoned coins are later resurrected, leaving 18% of coins to fail permanently.”

6. E6 As The Bitcoin Price Plummets, Its Dominance Is On The Rise Forbes · 27 November 2018

   “Elsewhere, amongst the other top five cryptocurrencies, Ripple's XRP is off by 90% from its all-time-high, Ethereum's ether is down by 92%, bitcoin cash 95% lower, while EOS (which peaked in April this year) is down by 85%.”

7. E7 As The Bitcoin Price Plummets, Its Dominance Is On The Rise Forbes · 27 November 2018

   “Bitcoin's epic bull run last year, that saw its price soar from under $1,000 at the beginning of 2017 to almost $20,000 towards the end of the year, dragged hundreds of so-called alt coins along with it—with many of them now collapsing entirely.”

8. E8 CoinGecko 2018 Full Year Cryptocurrency Report CoinGecko (hosted on SlideShare) · 15 January 2019

   “Prices for most cryptoassets fell anywhere between 70% to 95% from their All-Time-High.”

9. E9 These Are the Worst Performing Cryptocurrencies of 2018 - So Far Bitcoin.com News · 31 March 2018

   “Bitcoin Diamond: Astonishingly, someone once paid $105 for this garbage. It’s currently trading at $2.19. That’s a 98% retrace.”

10. E10 The economic potential and risks of crypto assets Bruegel (Policy Contribution Issue n˚14) · September 2018

    “After a peak of above $800 billion (January 2018), it fell to around US$200 billion (August 2018).”

The evidence shows that most coins fell roughly 70–95% from their highs, but this range is measured at year-end 2018 (E9), not at 15 October. It also shows several named coins down 90% or more (E2, E7, E10). No item counts how many coins had fallen 90–99% as of 15 October 2018, so the evidence cannot say whether that was thousands or hundreds, and it cannot place the typical decline in one criterion band.