https://www.smithsonianmag.com/history/how-theodore-roosevel...
You have to look at the history of each individual park, some started out as government land and remained such, others were private resort islands, etc.
But the same kind of private interest taking an interest in the affairs of state has its dark side too: Thurston also was the author of the “bayonet constitution” which undermined the Kingdom of Hawaii's sovereignty, and formed the ‘committee of safety’ which enlisted the US Marines in a coup that overthrew Queen Liliʻuokalani, and installed Sanford Dole (the fruit guy) as and President, and ultimately brought about the annexation of Hawaii.
Do you have a cite for that?
BTW, donating to charity is tax deductible. For example, if I donate $100 to charity, I can deduct $100 from my taxable income.
My choices:
1. paying taxes: I pay $20 2. donating to charity and deducting it from my income: I pay $100
I'm $80 worse off financially by donating to charity rather than paying taxes. As a tax avoidance scheme, donating to charity doesn't deliver.
Now, obviously your charity still needs to act as a charity so that money can't go back in your pocket but there are plenty of things the charity might spend it on that are in your financial interest and because you founded it, you likely have sufficient influence over it to make that happen even if you don't formally personally make its decisions.
Also, if you donate $100 in stock to a charity, that deducts your taxable income by $100 but it doesn't cost you $100 in income. Arguably a more egregious example for this is high art where you can create and destroy value through auctions (i.e. the value of your donation may be massively inflated compared to what you paid for it).
How do you think Carnegie's libraries across the country benefited Carnegie financially?
That said, the actual reason for his philanthropy seems to be fairly well documented: he did almost all of his philanthropy in the last two decades of his life (i.e. past what we would now call the age of retirement) and he was regarded as a shrewd business man up to that point and is now instead remembered as a generous philanthropist instead. So in other words, it was a very successful PR campaign to establish his personal legacy to survive his physical existence (i.e. "to secure his legacy" as the comment you originally replied to stated).
That said, he was also supportive of the ideas of progressive taxation and an estate tax, so the philanthropy may have simply been an act of last resort to part with his money when the government won't take it away through taxation. In that light it sounds more like his philanthropy aimed to meet the needs the welfare system failed to address. This is very different from the kind of philanthropy most billionaires (or "tycoons") get/got up to who are often very much against being taxed more (sometimes even despite publicly stating the opposite).
https://www.washingtonpost.com/news/retropolis/wp/2018/04/09...
https://scholarlycommons.pacific.edu/cgi/viewcontent.cgi?art...
Sequoia National Park - 1890
Yosemite National Park - 1890
Teddy Roosevelt - president from 1901 - 1909