Three years ago I wrote a post about sailing expenses after 2 years of sailing.
So here it is again, updated:

Monthly in 2 years Monthly in 5 years
Food* 226.16 211.0
Going out* 185.81 129.75
Marinas and Boatyards* 351.03 325.68
Fuel/water* 76.50 51.79
Insurance* 67.26 95.87
Chandlery and other maintenance* 500.00 591.98
Customs and immigration* 0.00 22.83
Non essential* 0.00 81.33
Total* 1406.75 1510.80

Explanations:

Food - got reduced because of careful planning and buying in bulks in Gran Canaria before Atlantic crossing, or in Dominican Republic before sailing to Bahamas, or just buying dairy products in French islands in the Caribbean. Not to mention there were two of us in the last three years but we were cooking more.

Going out - eating and drinking onshore including tickets to museums or car rentals.

Marinas and Boatyards - I was surprised it was less but it makes sense as I was spending way more in the marinas of the Mediterranean basin.
And after buying a water-maker the only island in the Caribbean we had pay for marina was Bonaire because we had to wait for mooring buoy to be available and then 2 months for buoy itself.
Also this subject includes expenses on labour which included refurbishment of the rudder in Las Palmas and levelling up waterline and moving to hard antifouling in Grenada.

Insurance - it got increased dramatically for Atlantic crossing and the Caribbean basin and I doubt it will ever decrease, especially after this.
P.S. they've changed their mind and we are insured but I have to overpaying for boat value.

Chandlery and other maintenance - toys, baby! That is the largest piece of expenses. From a simple screw driver to dinghies, outboards, water-maker or freezer. Not to mention electronics and batteries which are now all installed by me :)
To be honest - it could be way less as it is taking nearly 40% of total expenses, but safety plays an important part in it and I wanted to have a reasonable life and not to become a sea gipsy.

Customs and immigration - 0 in Europe and it is actually quite small amount in total as nearly half of it is duty taxes for stuff I've ordered to Aruba from the United States.
(better order to Curaçao as you can claim it as a boat in transit).

Non essential - scuba dive lessons and gear, spear fishing and free diving gear. Most of fishing stuff is included in chandlery expenses.

Total - nearly 16000 nautical miles in 5 years, but I am cheating a little bit because I am back at work and just have to pay for boatyard fees, insurance, new toys and random visits.

All this does not include the amount I had to put before launching Alka into water which is 10% of the boat price or 20k (whichever is bigger) if a boat is not prepared to be lived onboard full time, and, in my opinion, it does not matter if a boat is used or new. But you might be more lucky if you'd buy a well maintained blue water cruiser straight away.