A woman of her means is not accustomed to life on the run.
Life on the run is a Hollywood thing - the CIA isn't going to kick down her door and blackbag her back to the US. If she leaves the US, she is effectively gone unless she does something really stupid.
The FBI generally works through Interpol to bring back international fugitives (for example, Tamara Dadyan) but will also "blackbag" fugitives if necessary. It's just not necessary to do that very often.
There's also plenty of countries that would enjoy harboring a wanted US person.