Too much ranting about "liberalism" Actual reasons white Rhodesia lost the war:
1) They were outnumbered 20 to one. A tiny population of 220 thousand whites could not indefinitely rule over close to five million blacks.
2) Nobody would recognize them as a legitimate regime. White rule had been previously based on affiliation with the British Empire. The British government position on decolonization was no independence before majority rule which, from their point of view, was a reasonable position given that demographically it was a black African country.
3) Once Portuguese colonial rule of Angola and Mozambique ended, Rhodesia was geographically isolated and surrounded by enemies leading to a loss of trade partners and inability to prevent infiltration of it's borders. The only remaining ally was South Africa.
4) Rhodesia was not politically liberal during the time Ian Smith was in power. It was a right wing government led by a charismatic political leader. In some ways it resembles Netanyahu. Smith didn't try to compromise until he was forced to, and by then it was too late to get favorable terms.
5) the rebels/terrorists did have some successes. They shot down a commercial airliner and killed many of the survivors, and they also blew up the principal oil supply depot of the country. These events were demoralizing.
6) Although the sanctions did not cause immediate economic collapse they did have a long term effect of weakening the country by restricting exports of tobacco ( the principal crop) and limiting foreign exchange in other areas as well. I can post a link to the economic analysis that claims this.