I was there. The attendees were mostly older than 40, many in wheelchairs, pushing walkers or with an aide. It was an opportunity to see and talk to others with similar concerns.
If someone wants to use the peaceful gathering to bring up other violence at other gatherings, that seems perfectly fine. It does nothing to diminish the fact that this event was peaceful. I also attended the Women's march. It was peaceful too. 
There have been violent clashes at other anti-Trump rallies. As a percentage of the people who participate, that has been way less than 1%. Many of those who have clashed were looking for an excuse to "rage against the machine". They are the ones that got more coverage than their numbers deserved because if it bleeds, it leads. 
I don't believe any health care program is going to be affordable with good coverage. But making 200 million people "shoppers" in a system that is hard to understand and that hides costs will not lead to competition and lower costs.