I think that, if he comes across this thread, he'll be reading people's reply with a smile on his face and also taking note of the importance ideas people are indirectly passing to him. Anyways I so much believe in his wonderful creation (Bitcoin) and my honest message to him is that he made the best choice of staying anonymous and I hope his identity stays that way for eternity, cause it's  been a strong force against bad governments that had the intention of gaining control over it and using it for their selfish interest just like the fiat money. On a second thought am not aware if you're alive or late but nevertheless it's just about 15years since creation and it's gone global for different use cases, you're gradually transforming the finance world into something dynamic for the future, I salute you for such a unique and wonderful creation.

We aren't really chatting though but making comments that can help cheer up someone, that can help motivate and keep informative as well. My message to Satoshi would be this simple because he is capable of delivering on the promise.

Dear Satoshi,
It's been a revelation to have known you, although not personally, but due to one significant fact of your achievements and contributions to the success of the Bitcoin and cryptocurrencies idea.
I know Bitcoin still has much more value to offer the world and although my country still needs to see the light and adopt or legalize the use of BTC, I for one would love a Christmas gift of just 1 BTC for investment purposes. Thanks.

My Best Regards,
Cryptomultiplier

My message to Satoshi after expressing my great gratitude and deep thanks to him for his invention that changed the world I want to tell him to stay hidden.

One of the best things that Satoshi did after completing his great invention Bitcoin is to disappear from sight and did not reveal his identity, this increased the shine of Bitcoin and gave it a very beautiful legendary glimpse.

Finally I want to ask him are you satisfied with what Bitcoin has reached now? Was this really your dream or did you want something different from what we have now?

The real Satoshi wasn't alone. Satoshi's a pseudonym used by more than one person that's why it's possible someone from Satoshi's reading the messages. I've written about it Why did Satoshi use GB British English and international English ?

I would just tell that group/person to just be happy about what they created, have no regrets whatsoever and enjoy their time. We bitcoiners can handle the rest of the work from here.

They should never reveal themselves even if they actually get identified in real. Let people speculate as much as they want, they would be only wasting their own time.

When I read this comment I actually laughed, but come to think of this; don't you think that would cause so much heart break to world at Large, 16 years is it a joke?
Bitcoin has gained trust to toy with people's hearts, instead I will message him to make himself and family hidden. Of course I believe by now his family are no place to be found and the name Satoshi may not corelate with their real name otherwise anyone who bears same name can be tracked.

It is my pleasure to write this message to appreciate Satoshi for your sacrifice to remain anonymous over 16 years, for BTC to dominate over the world, I will advise you to remain anonymous because there are some people who are not happy about the BTC you have created to help humanity. I believe  you are in good health and your lovely family too, I don't have money to give to you to appreciate you for all you have done to bitcoiners in this 16 years BTC has spend on earth.

I never regret for the time I spend in reading some online books that related to BTC when I was in school, it has brought a good results that made me not to depend on guys before i can plant my hair, buy clothes,  pay house rent, food stuff but through BTC am financial buoyant.

Your post is asking for expression of gratitude to Satoshi Nakamoto while the titled topic is a different one, asking us for a message to him.

Let me react to the first – gratitude. Of course, anyone in this industry that isn't grateful to Satoshi for the business atmosphere and engagements he equipped us with by that singular act of creating Bitcoin is an ingrate. I, for one, am super grateful to him for this. I've gained maximally, both in knowledge and finance. All thanks to Satoshi.

On the open message part, I want to urge Satoshi to continue to remain anonymous. His presence isn't anymore needed. In fact, revealing himself now will become problematic for the industry. We've seen how government has continued to go after creators and developers of cryptos in recent time. It's the same thing they will do to him if they knew who he was.

If you have a message for satoshi, just leave his account the message that you want just like what I did but of course with a positive one.

Well we can never be too sure about that
Maybe once in a while he checks on the forum and go through the messages
And I think he might actually smile going through topics like this😅

So I encourage you to drop a message