I would rather say that suicide and Nibbana are polar opposites, than “Suicide is similar to Nibbana”. North and South Poles are at opposite ends of the planet, and both are equally glacial, or very cold. I am NOT saying “Polar Opposites” in this sense. Nibbana is the rightful escape from depression, and suicide is a momentary escape. I say this because you end up being in the same state in your next birth. One’s character “(gathi)” determines one’s future births.
Suicide statistics tell us that up to 15% of those who are clinically depressed die by suicide.. This brings home the message that we underestimate the severity of mental suffering compared to our physical suffering. If you would go more into Buddha’s Dhamma, you will get to see how our minds control our physical bodies. Then you will begin to understand how the “gathi” from the past life is conditioning your present thought.
Changing to a “gathi” of a Sotapanna is called a change in lineage where one becomes an Ariya or a Noble person and never turning back to the conventional way of life. That is the road to Nibbana – the Answer. By listening to, and reading & understanding the deeper meanings that lie within the first 58 books ever written on Buddha Dhamma, one becomes a Sotapanna (a Stream Entrant). Then by furthering the understanding through proper Guided Meditation, one goes up the ladder towards Nibbana.
Suicide would only make things worse in the “long term” in the rebirth process. Thus it is never too late to start at any stage in your life, this Path to Nibbana. Human life is rare and should not be wasted at any stage. But if you are one who entertain suicidal thoughts, as in to the point that you can’t imagine getting out of bed in the morning tough, you need help. And there should be no shame in seeking it.
A significant part of our suffering comes from the mind. Even some famous and rich people that we know could not bear this mental pain to such an extent that they committed suicide. One could be living in a mansion with a burdened mind and could even commit suicide, while a poor person who has learned the deeper Dhamma that lies hidden beneath the conventional, could be living in a hut with a peace of mind content with what he/she has and knowing that any hardship is just for a brief time (in this life).
Why is Nibbana totally different to suicide is because ONLY a person who truly understand the true meaning of ANICCA attains Nibbana, whereas a person who is all wrapped up in the notion of ‘self’ / ‘Atta’ may go the suicidal way.
The word “atta” can have many meanings depending on the context. In the conventional sense, “attā” means “a person”. The deeper meaning of “atta” is “in full control” or “the essence” or “the truth that is timeless”. Just like the word “anicca“, it is not possible to translate to English. One must get the idea by learning how it is used in various situations. The opposite of “atta” is anatta (“helpless” in case of a living being or “useless” in case of an inert thing) as in the Tilakkhana.
What I give above is a deeper meaning to two key words that are found in this Dhamma Path. If you look at suttas, there is no clear grammatical structure. It is the sound that gives the meaning and most verses have “double meanings”. There is an apparently simple meaning, but deeper meanings are hidden most times. A Sotapanna begins to see this higher truth – the “Paramatta Dhamma” - that lies beyond the conventional truth that most of us are accustomed to.
Paramatta comes from “parama” + “atta“, where “parama” means “at the highest level” and “atta” means “the truth that is timeless”, the deeper meaning. This is a deeper ñāna that a person who is well into this Noble Eightfold Path sees. It is fourfold, and is called Patisambidha Ñana whch in other words can be said as “atta, dhamma, nirutthi, patibhāna“. One who gets to see this two levels of Dhamma will not take “atta” as “a person” or “a self”, and will see Nibbana, and will eventually achieve Nibbana.
As for the ones who are fixed on the conventional meaning to the word “atta“, as well as for anatta, nicca, anicca and many other words, they have a likelihood of equating Nibbana with Suicide. This is one of the main reasons for people to equate suicide with Nibbana.