If everything else goes south, the client sues the lawyer — and the best defense is “here’s where I said that might happen.”
Spot on. EDIT: On further thought, there's a wrinkle, which is that NOT being super-conservative can be good marketing for a lawyer. In a 95% confidence situation, consider the lawyer who tells the client, "here are the pitfalls, but IMHO they're an acceptable business risk [one of my favorite formulations], so if you want to do it, then go for it!" That lawyer is likely to have a happy client who, if asked for a recommendation by a third party, might refer the third party to the lawyer.
(Of course, this presupposes that the lawyer has enough experience to be able to confidently weigh the business risks — and that a 5% disaster doesn't befall the client.)
Ultimately though, there is an important thing that GP’s friend missed out on. Lawyers do not tell you what to do, rather instead they advise you of risk on what your options are. It’s your responsibility to decide how much risk you are willing to bear.
Example: Many years ago, on the afternoon of the last day of the quarter (when lots of business gets closed for financial-reporting purposes), a software-company client's VP of sales — with whom I'd worked for years — called me and described a situation, saying "the customer wants to change our contract to say X." I asked a couple of questions and then said "there's always the possibility of Bad Situation B coming up, but it's unlikely, and it'd be manageable if it did — go ahead." The VP said "Thank you — bye!" and slammed down the phone. (That VP went on to CEO positions at two other companies and uses me to this day.)
I agree with it completely. But I've been doing this long enough that I'm not embarrassed about telling clients what I think and what I'd do if I were in their shoes, and my clients aren't the sort to just passively do what I tell them.
(It also helps that I've been a solo public-company general counsel — meaning that for a number of years I worked very closely with sales people and became acutely aware of the importance of getting deals done, as opposed to just identifying and flanging up risks.)