Have they not traveled through the earth and observed how was the end of those before them? They were greater than them in power, and they plowed [or excavated] the earth and built it up more than they [i.e., the Makkans] have built it up, and their messengers came to them with clear evidences. And Allāh would not ever have wronged them, but they were wronging themselves.
(9. cont - and see what was the end of those before them They were superior to them in strength, ) meaning, `the nations of the past who came before you were stronger than you to whom Muhammad ﷺ has been sent; they had more wealth and more sons. You have not been given one-tenth of what they were given. They stayed longer in this world than you will stay. They were more civilized than you and were more prosperous in the land than you.' Yet despite all that, when their Messengers came to them with clear signs, while they were enjoying their life of luxury, Allah punished them for their sins and they had no one who could protect them from Allah. Their wealth and sons could not protect them from the wrath of Allah in the slightest, and Allah was not at all unjust towards them when He sent His punishment upon them.
وَلَـكِن كَانُواْ أَنفُسَهُمْ يَظْلِمُونَ
(9. cont - but they used to wrong themselves.) They brought destruction upon themselves, when they rejected and mocked the signs of Allah. All of this only happened because of their previous sins and their rejection (of the Messengers). Allah says:
Ma'arif al-Qur'an
Mufti Muhammad ShafiOn ayahs 9–14
أَوَلَمْ يَسِيرُوا فِي الْأَرْضِ (Have they not travelled on earth - 30:9). It means that the Makkans live in a land where there is neither any cultivation and industry nor any tall and beautiful buildings, but for the sake of trade they do travel to Syria and Yemen. So, have they not seen, during the course of their trips, what was the fate of the earlier people, whom Allah Ta’ ala had endowed with skills to make use of the land? For instance, they had the skill to draw underground water by excavating the earth for irrigating fields and gardens, and dig out concealed precious minerals, such as gold and silver, and make use of them to their benefit. For their advanced skills and way of living, they were regarded as civilized nations. But they got engrossed so much in material life, transitory luxuries and comforts that they forgot Allah Ta’ ala and the Hereafter. Then, Allah Ta’ ala sent prophets and books to remind them of their duties, but they did not pay any heed. Ultimately, they were overtaken by Allah's wrath even in this world. The ruins of their desolate cities still stand witness to their destruction. At the end of the verse it is suggested to ponder whether they were subjected to any oppression from Allah Ta’ ala, or they subjected themselves to their own cruelty by accumulating causes of the divine punishment.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 5–9
At the time of the advent of Islam, there were two very great empires in the world —the Christian Roman Empire and the Zoroastrian Persian Empire. There were constant clashes between these two. In the year 603 A.D., Iran (Persia) attacked the Roman Empire, taking advantage of certain weaknesses in the latter. The Romans suffered defeat after defeat, so much so that by the year 616 A.D., a large part of the Roman Empire, including Jerusalem, had been captured by the Iranians. The Prophet received the prophethood in the year 610 A.D. and he started upon the task of explaining the Oneness of God in Makkah. This was the period of the struggle between monotheism and polytheism in that city. The polytheists of Makkah, taking their cue from the events on the border, told the Muslims that their polytheist brothers, the fire-worshipping Zoroastrians, had defeated the possessors of the Book and brothers of the Muslims (namely, the Christians) and that in the same manner they (the polytheists of Makkah) would finally overwhelm the Muslims. At that time, completely against the prevailing trend, the Quran predicted that within ten years, the Romans would regain supremacy over the Iranians. Roman historians say that immediately thereafter the vanquished King of the Romans, Heraclius, started undergoing a mysterious change, so much so that in the year 623 A.D., he led a retaliatory attack on Iran. In the year 624 A.D., he achieved a decisive victory over Iran. By the year 627 A.D., he had recovered all his occupied territories from the Iranians. Thus it was proved that the Quran was a revelation from God, as nobody else except God could have made such statements about the future so accurately. Moreover, these events indicate that victory or defeat are directly in the hands of God. It is according to His decision who gains and who loses power. The downfall of a nation and the rise of another nation, to all appearances seem to be ordinary, normal, worldly events, but appearances have an inner aspect to it. Every event is caused by a number of angels of God, though they are not visible to ordinary human eyes. Similarly, there is an invisible aspect of the present, outward world and it is the world of the Hereafter.