I'm inclined to write an answer with a different tone to that of the other one: namely, the Dutch never had control of the seas and as such they couldn't lose it.
The strategic options that a naval power has include the control of the seas, denying the seas to the enemy, or, in essence, fighting on an equal footing (i.e., not using overpowering numbers to prevent an enemy from taking to the seas but also not using asymmetrical forces to prevent the enemy from sailing and slugging it out until a victor emerges in battle after battle).
The three 'classic' examples that are generally given for 'control of the seas' are those of Athens in the Peloponnesian War, the United Kingdom from Trafalgar to 1914, and the United States in the later part of the 20th century.
In the Age of the Sail, effective denial of the seas could be accomplished by obtaining supply bases in areas where the potential enemy had none: this would make combat in these areas a logistical impossibility for the attacking force (lest it be gathered and sent to fight the enemy on a win-or-die basis. The Portuguese, the Spanish, and the Dutch, while possessing grand trading empires, only sought to deny the seas to their potential opponents in very specific circumstances, such as the Portuguese in the Indian Ocean, the Spanish in the Pacific Ocean, and the Spanish–Portuguese dividing up the world for their own colonization.
The Anglo–Dutch Wars are brought out as an example of the Dutch supremacy. I embrace this in full with the caveat that the Dutch skill in seamanship and naval leadership was such that they fought others, sometimes outnumbered, sometimes outnumbering, when and where they had to, but they didn't pursue a policy of denying the sea to their potential opponents (at least no more than anyone else—Portugal as an example—in the 17th century would have). Neither was there a specific policy of outnumbering an enemy in warships like the United Kingdom would have in the 19th century.
Dutch power was mercantile power (Wikipedia):
During the Dutch Golden Age in the late-16th and 17th centuries, the Dutch Republic dominated world trade, conquering a vast colonial empire and operating the largest fleet of merchantmen of any nation.
Also (Wikipedia):
The States-General had only two direct sources of income: it taxed the Generality Lands directly, and the five Dutch admiralties set up under its authority, financed their activities nominally from the Convooien en Licenten levied on trade. ...
Mercantile trade brought risks of shipwreck and piracy. Such risks were often self-insured. The East-India Company armed its vessels, and maintained extensive military establishments abroad, thereby internalizing protection costs. Arming merchantmen was quite usual in those days. However, the type of cargo vessel most often used by the Dutch, the Fluyt ship, went usually without guns, or was but lightly armed.
Regarding the fluyt (Wikipedia):
Unlike rivals, it was not built for conversion in wartime to a warship, so it was cheaper to build and carried twice the cargo, and could be handled by a smaller crew. Construction by specialized shipyards using new tools made it half the cost of rival ships. These factors combined to sharply lower the cost of transportation for Dutch merchants, giving them a major competitive advantage. The fluyt was a significant factor in the 17th-century rise of the Dutch seaborne empire.
The standard fluyt design minimized or completely eliminated its armaments to maximize available cargo space, and used block and tackle extensively to facilitate ship operations. ... At times fluyts were also armed and served as auxiliary vessels, which was a common practice in the Baltic Sea.
Hence, insofar as it existed, Dutch command of the seas was mainly dependent on trade that generated income, directly allocated by the Admiralties for the construction of ships, as well as the type of combat in those days, i.e. mobilizing non-specialized warships for combat in times of war, which the Dutch were able to do in great numbers due to their power as a trading nation. This was further enhanced by the institutionalization of officer training and standards, e.g. Tromp and de Ruyter who understood the method of war at sea perhaps better than their contemporaries (with several English naval leaders being generals who were thrown on ships in time of need).
Nevertheless, the Dutch did not have (or strive towards) peace-time command of the seas, i.e. denying the use of the sea to its neighbours, though they strove towards mercantile equality (which would give them, the better, faster, and more specialized traders, the edge).
