Have there been any autobiographies or firsthand accounts of these struggles?
The comment posted by "John Doe, Esq." (timestamp being May 22, 2014 at 3:56 pm) in this article will be of your interest. The reasons for his anonymity are obvious, but this is one of the rarest samples of sincerity an outsider will ever obtain from an attorney, let alone one who currently profits from the legal system.
Every time a lawyer makes frivolous allegations like in the El Chapo example you mentioned, that lawyer is proving to the world that he has lost morals altogether. That blatancy is an impermissible deviation from the lawyer's job of procuring that due process is afforded to his criminal clients. In those instances, one cannot expect there to be room in the lawyer's mind for remorse or to even entertain a moral dilemma.
Without ever condoning the despicable acts that many practitioners incur, I can understand how the credentialing process (at least in the US) is one early factor toward severing their integrity. There are other factors such as the glamour and fiction built around the concept of "lawyer", but long-term these exert lesser psychological pressure on what a lawyer does with his life & career.
J.D. programs are overpriced and make US lawyers start their career with more indebtedness than most other graduates. Of course, a prerequisite for starting their career is that the J.D. graduate passes the Bar exam, an exam which many J.D. graduates fail. For a small fraction of the cost of a J.D. degree you can earn a graduate degree that is far more edifying than the job of obfuscating the jury for the benefit of wrongdoers.
Having spent 2-3 years and a fortune on a J.D. degree (in addition to the undergraduate degree) and passed the Bar exam, the lawyer feels so invested in the hole that usually he senses no option but to lend himself to the dynamics of litigation business. Keep in mind that the skills & body of knowledge imparted in a J.D. program are hardly transferable to other fields. This is different than, for instance, the physicist or the electric engineer who can easily transition to mechanical/industrial/computer engineering (by the way, it is easier for an engineer to internalize matters of law than for a lawyer to attain an equivalent proficiency in physics & engineering). From that standpoint the lawyer is trapped, but --for whatever reason-- he does not want to switch careers.
From then on, the average legal practitioner embraces a downward spiral for the sake of money & influence. In the case of small-town lawyers, this stays at the level of mere survival. But other lawyers do succeed in rubbing elbows with the elite (again, lending themselves to unconscionable acts) till things blow up. One recent, prominent example of that "success" is lawyer Michael Cohen.