Unless you have a large amount of money to begin with, and then some means of more money coming through, you will have great difficulties. It is all very well to make a list of all the species that you want to display, but actually getting them may not be too easy. Then there is the cost of feeding all your animals - very high. Not to mention the cost of construction of the exhibits, the many ''hidden'' costs of maintenance, the many fees you will have to pay to various authorities for permissions etc.. Also consider that that more animals you have on display the more staff you need to pay plus other staff, besides keepers, such as gardeners, catering etc.. The more you grow the more expensive it gets, and it never ends! What about the cost of insurance - if you can find a company who will insure you; many will not, and those that will are very expensive. Also consider that even if you are covered by insurance that can be cancelled, usually a few days before the policy is due to be renewed. (Been there,done that!). And these are only some of the things you need to think about; there will be many more that will crop up when you least expect them. Which comes back to the money. The income from the gates etc., will probably not be enough, especially in the beginning when you need it the most. Another ongoing thing you will require is advertising, and that is a bottomless bucket that you really can't do without!
Good luck though, and I never regretted having a go, although very little money came into my pockets in the ten year experience.
You can’t imply things about @Batto if you haven’t read the WHOLE thread