I don't think any PhD student will tell you graduate school is easy,
but I also don't personally know anyone who has gotten their PhD that
said they wouldn't have if they had the choice again. There are
horror stories you will hear from time to time of a terrible adviser,
but I believe for the most part there is a great deal to learn in grad
school, and many people I've spoken with say it was a time period
where they really developed as scientists, so to speak. The most
important aspects to be taken from grad school, as Ravasz mentions,
and what I've heard from friends in PhD programs, is learning how to
plan out and manage a project consisting of many different experiments
that span years worth of time, and having the ability to manage all
that data and turn it into something useful at the end.
Different advisers have different philosophies on what their grad
students are there for;
to be a "robot" and pump out data to turn into papers to pad the PI's
CV and bring in more grant money
or
http://people.bu.edu/dougd/studentInfo.html
Read the 9 bullets of advice from that person's lab. I came across
that one day looking at programs and it sounded like a great
philosophy for an adviser to have!
Many many people have succeeded in life without attending grad school,
or any school at all, and a few have become quite wealthy. There are
also many many people who have succeeded in life and attended grad
school, and a few have become quite wealthy.
I don't think (though there are always exceptions) that many people
get a PhD simply to get a better job, I think you really have to enjoy
what you are studying to make it an enjoyable experience. Many people
I know in programs just simply love science, and while that might make
the 10 hour days bearable, it doesn't mean it's all going to be easy
going from day 1.
Figure out what it is you want to do in life and then decide if a MS
or a PhD, or neither, would be a good choice.
An extremely over simplified way of looking at it would be (and this
never applies in 100% of cases, it's just what I've seen personally
and heard through the grapevine): BS degree = bench monkey for life
with the potential to move up the ladder if you stay at the same
company for 30 years. MS = can be a manager of a small lab perhaps,
but I've never heard of a full professor with just an MS, and probably
never a senior scientist.. PhD = full professor at any university in
the world, highest research positions in companies, can manage their
own labs and supervise PhD students.