The 180 mark is also the start of the DIA's parabolic move on the chart from Nov. '17 through end of Jan. '18 where a 44% increase occurred in 13 months with an average 3.4% increase per month during that time.
Before last parabolic thrust up, the DIA up move from Mar. '09 through end of Nov. '17 was a 155% increase over 92 months with an average 1.7% increase per month during that time. Giving back all the final parabolic move probably isn't unreasonable to help reset some balance.
Everyone was so worried about the market cap loss in potential crypto unwinding. That is dust compared to the market cap loss that would accompany an equities unwinding if DIA were to hit 180 and all the other major markets worldwide pullback in a similar fashion.