Very odd perceptions here. Non-invasive cards still reads echos, nucs, does inpatient, etc. On the outpatient side, sure it's a lot of chronic disease management and such, but better to be focused on one organ. Typically in any specialty you have to be ok with the bread and butter stuff. Not sure why you think folks would regret non-invasive cards. People like it. Some don't like being in the cath lab or doing procedures. There's plenty of medicine in cards and procedures are relatively small part of it. With downward pressure on invasive procedures from insurance companies and the like, I wouldn't bet on having a cards career heavy on procedures.
LIfestyle and such is highly variable depending on setup. I know a person who does only outpatient cards affiliated with an academic center, no imaging, one inpatient weekend a month. Another setup where invasive gen cards is basically 7-5 job, call is something like q7 mostly by phone as hospitalist/ICU is primary and cards is consultant. Not a bad setup. Another PP IC guy that basically has a similar setup mainly because he chooses his patient load and procedures carefully, of course splitting stemi call with others though. Then there's IC group that basically hustle working 7am-11pm, doing tons of procedures and busy AF but making bank. Keep in mind a lot of specialties you still need to take call.
I see pay starting at 300k in major desirable cities (which are still competitive) and going up from there. Personally I'd still do it even if it paid as much as PCP just because I find the work and such that much more interesting and rewarding. If you want to make the most money for least work, cards or medicine overall may not be the best fit for you.