THE ROTHSCHILD FAMILY IS MALIGNED BY MANY PEOPLE IGNORANT OF THE FACT THAT THEY ARE DOING THE WILL OF GOD. This Is Because Most People Do Not Understand What Is True And How God Operates. The idea that people have freewill and God can predict the future is beyond the capacity of mortal humans to grasp. It's a different matter when one is enlightened by the Spirit of God.
The idea of “conspiracy theory” sounds like “the theory of evolution” and nothing more. A vacuous concept based upon a desire to discredit what might be true.
As for the Rothschilds, what has paralleled their prominence in the nineteenth century has been the industrialization and change in living standards for billions of people. It may be true that Rothschilds have their own agenda, but it is also true that living standards have increased for the average person since the days of squalor that existed for many who lived in Europe.
The Rothschilds were responsible for the expansion of the railway systems and utilizing oil as means of energy and, even, the popularizing of the motor vehicle. This is because they were behind those who lent the money for the viable projects, if they did not always do so conspicuously.
The Rothschilds are responsible for modern day Israel's existence and for it becoming a prosperous nation. The National GDP of Israel is $35,431 per person and the country is ranked 29th in the world in 2015, with its neighbors Lebanon 82nd ($13,938 per person), Egypt 99th ($10,891 per person), Jordan 100th ($10,880 per person) and Syria 139th ($5,100 per person). 
The living standard today of $35,431 per person has increased even 41.7% more since 2008 when the Haaretz reported in an article entitled 60 years of economic prosperity
Very few countries have managed to grow and prosper so quickly in 60 years, from a standard of living of $3,100 per person in 1948 to today's $25,000; from a country of 600,000 residents to 7.3 million; and from an orange exporter to an international high-tech power. 
Had the Rothschilds not invested in Israel, in all probability, the nation would be like those countries that surround it, with a gross domestic product per person around one third of what it produces today. But the Haaretz points out that the standard of living has increased from $3.100 in 1948. On 2015 figures that standard of living for those who were living in Israel has increased 1100 percent from $3.100 per person to $35,431 per person.
This is what the Bible says will happen:
Therefore say, ‘Thus says the Lord God: Though I removed them far off among the nations, and though I scattered them among the countries, yet I have been a sanctuary to them for a while in the countries where they have gone.’ Therefore say, ‘Thus says the Lord God: I will gather you from the peoples, and assemble you out of the countries where you have been scattered, and I will give you the land of Israel.’ (Ezekiel 11:16-17)
In 1900 AD, not too many thought the Jews would return to Palestine. Instead the majority of people thought the Bible was just a fairy tale. After all, prophecy is the signature of divine inspiration.
No one can make predictions like those found in the Bible with such accuracy unless the end is known from the beginning. So irrespective of what people say about the Rothschilds, it seems that they are being used of God to bring about His purpose.
Why do the nations conspire, and the peoples plot in vain? The kings of the earth set themselves, and the rulers take counsel together, against the Lord and his anointed, saying, “Let us burst their bonds asunder, and cast their cords from us.” He who sits in the heavens laughs; the Lord has them in derision. Then he will speak to them in his wrath, and terrify them in his fury, saying, “I have set my king on Zion, my holy hill.” I will tell of the decree of the Lord: He said to me, “You are my son, today I have begotten you. Ask of me, and I will make the nations your heritage, and the ends of the earth your possession. You shall break them with a rod of iron, and dash them in pieces like a potter’s vessel.” Psalm 2:1–9)
Whatever people say about the Rothschilds, it is because of what is prophesied in the Bible, many Christians rejoice in what they have done, because they see this as the fulfillment of biblical prophecy. This is not to say that the Rothschilds are hearing the voice of God and are worshipers of Lord Jesus Christ, just that while they are doing what comes naturally to them, they are doing what God knew would happen under the circumstances.
You might call that a conspiracy theory. I call it amazing. Bible prophecy is incredible and those who dismiss it, do so at their peril. When people reject the obvious, they have to believe a lie and say it is untrue—maybe, even if it means calling it a conspiracy theory.