People usually do not grasp the unintended consequences of who their property will be distributed to upon their death without an estate plan of some sort.
I had a client who had dated a man for 30 years before finally giving in to his multiple proposals. Unfortunately, the man passed away within the year of their marriage. The man had an estranged daughter from a previous relationship and had not had contact with her for decades. The man owned multiple assets, including the home he lived in with my client, but because the couple was recently married, all the property was the decedent's separate property and my client did not have a community property interest in any his assets.
The man did not have an estate plan. Under the laws of intestate succession, all of his property would pass to his wife and his estranged daughter equally. Additionally, a probate would be necessary to effectuate the transfer of the assets which included multiple bank accounts and real properties to the wife and estranged daughter.
You can imagine my client's surprise and chagrin when I explained that not only would her husband's estate be subject to probate, but that his estranged daughter would need to be noticed and she would be entitled to 50% of all the assets, including the home my client had resided in with this man.
On another occasion, I met with a successful single man who was interested in estate planning. He asked me where his assets would go if he passed away without directing distribution of his property by a Will or Trust. He didn't have children and both his mother and father were living. I explained that under the succession laws of CA, his property would go to his parents in equal shares, subject to a probate proceeding.
He was mortified. It turned out that his parents were divorced and he did not have a relationship with his father in any respect whatsoever. And he explained, he would not want anything he owned passing to his father under any circumstances.