I think crazy Nancy stepped down because:

1) if she's out of office, she's less likely to be targeted by investigations. Of the treasonous crimes she has committed in recent years as House speaker (insider trading in the hundreds of millions, and obstructing Trump's authorized preventive deployment of 20,000 national guard troops in Washington DC on Jan 6 2021, that would have prevented any rioting at all that day. She has never been held accountable for her obstruction of that security, her or Schumer. Let's see what happens when ACTUAL fact-finding of a Jan 6th investigation occurs now, under new Republican control.)

2) Things are imploding for her at home. Paul Pelosi was drunk and totalled an expensive car a few months ago, and Paul Pelosi clearly had a mistress in the passenger seat (facts suppressed by Democrat-friendly bay area police, and a Democrat zealot prosecutor's office. )
And then just a few months later, Paul Pelosi is caught at home with a male prostitute, and apparently a third man, according to initial now-suppressed police reports. Facts suppressed by local police, by the Pelosi-friendly DA's office, and the Democrat-allied news media. Anyone else in Paul Pelosi's situation, who totalled his car and injured another driver, and was clearly too drunk to even speak to police, would be IN JAIL already from the first incident.

And now the second David DePape incident.
As details of these two incidents inevitably come to light, public opinion of Nancy Pelosi and her corrupt inner circle will continue to tank. And perhaps result in charges for obstruction of justice, influence peddling on the police and local D.A., and more as other as-yet unseen lurid details come to light.

And remember, this is the same corrupt politician who locked down hair salons for everyone else in California, but then was caught ON VIDEO coming in, elitely priveleged to what she herself prohibited her constituents to have, wearing no Covid-mask she mandated otherss to wear, for a hairstyling any time she wanted. And when the salon owner released the video that went viral nationwide, the salon owner was intimidated to the point that she had to close her salon due to multiple threats, and eventually had to move her business to another state.

All manifestations of how Pelosi, and her nut-job corrupt party consistently operate, all coming to light. That Pelosi, roach-like, runs for cover from when the lights come on. She had a good corrupt and profitable run. But it's over now.