I know that there really isnt any answer to this but I would love to hear peoples opinions.
At what age/stage of ones life should one think about starting a trust.
I know some people who have all (or at least) a nice portion of their net worth in a trust.
Trusts vary in complexity and have a myriad of different purposes. On the surface, you need to understand the difference between a revocable and irrevocable trust. The latter is the hard, distinct entity that is used in estate planning to work around estate tax limitations (5.45 single, 10.9M joint lifetime on a federal level).
The most common revocable trust, is more commonly known as a living trust, which is what many of your friends likely have. The purpose of this trust is to simply drive assets to their desired location without the need for probate.
Probate is the court proceeding for the proving of the will, IE if you put a number of stipulations in your will for whom in your family should receive what, these things will need to be brought before the probate court in order for them to confirm the wishes, and retitle the assets accordingly. Probate is a process that takes time, is public, and introduces a contestable stage where disenfranchised heirs may challenge the will, forcing a drawn out process which may involve an unfavorable ruling.
Placing assets into a living (revocable) trust means that they avoid this probate process.
Not all assets should be placed into trust, as certain assets have intrinsic regulations that are best allowed to flow via beneficiary designation.
Beneficiary designation is the naming of those who will inherit your assets. Certain assets such as IRA accounts, bank accounts, and others will transfer on death to the named beneficiary. This named beneficiary supersedes any wishes left within the will. A common mistake is to name an ex spouse as the beneficiary of an old account, update your will to the new spouse but forget to update the beneficiary designation, meaning the Ex gets the account.
Revocable trusts assets are part of the estate at death, and are seen as pass through entities when it comes to estate tax.
Irrevocable trusts are considered external entities, they each have different rules and regulations, including look back periods where things are clawed back (often 3 years from time of 'gift' or funding) these entities take assets out of your estate and therefore at death you are not subject to the same level of estate tax as your net worth appears that much lower. However, taking them out of your estate can also mean that you lose access to the assets, so depending on the type of irrevocable trust, you might want to ensure you have enough money remaining and accessible to you (the Grantor).
Your friends most likely have assets in an revocable (living) trust. Those assets are likely a brokerage account.